drives: fix floppy speed test warmup and OFS block size reporting

The floppy speed test warm-up read was previously attempting to read
an entire track buffer. This large read could fail due to timing or
settling issues, causing the speed test dialog to abort immediately
because the error was treated as fatal.

Reduce the warm-up read size to a single block (typically 512 bytes)
to minimize failure risk while still ensuring the drive head is on
track. Additionally, treat warm-up read errors as non-fatal warnings
to allow the actual benchmark to proceed.

Also fix an issue where the block size for OFS volumes was being
reported incorrectly (e.g., 464 bytes instead of 488). The `Info()`
call returns the logical block size (488 for OFS), which was
overwriting the physical block size (512) obtained from `DosEnvec`.
The display logic then subtracted the 24-byte overhead again.

Prevent `Info()` from overwriting `bytes_per_block` if it has already
been populated by `DosEnvec`, ensuring the display logic calculates
the usable block size correctly from the physical size.

Author: reinauer

src/drives.c

@@ -301,7 +301,10 @@ void enumerate_drives(void)
             if (Info(lock, info)) {
                 drive->total_blocks = info->id_NumBlocks;
                 drive->blocks_used = info->id_NumBlocksUsed;
-                drive->bytes_per_block = info->id_BytesPerBlock;
+                /* Only update block size if not set by DosEnvec (which gives physical size) */
+                if (drive->bytes_per_block == 0) {
+                    drive->bytes_per_block = info->id_BytesPerBlock;
+                }
                 drive->dos_type = info->id_DiskType;
                 drive->fs_type = identify_filesystem(info->id_DiskType);
                 drive->disk_errors = info->id_NumSoftErrors;
@@ -587,18 +590,12 @@ ULONG measure_drive_speed(ULONG index)
     if (is_floppy) {
         io->io_Command = CMD_READ;
         io->io_Data = buffer;
-        io->io_Length = buffer_size;
+        io->io_Length = block_size;
         io->io_Offset = read_offset;
 
         error = DoIO((struct IORequest *)io);
         if (error != 0) {
-            debug("  drives: Warm-up read error %ld\n", (LONG)error);
-            FreeMem(buffer, buffer_size);
-            CloseDevice((struct IORequest *)io);
-            WaitTOF();
-            DeleteIORequest((struct IORequest *)io);
-            DeleteMsgPort(port);
-            return 0;
+            debug("  drives: Warm-up read error %ld (ignoring)\n", (LONG)error);
         }
     }