ide-floppy: start DMA engine in idefloppy_transfer_pc1()

Start DMA engine and set PC_FLAG_DMA_IN_PROGRESS flag in
idefloppy_transfer_pc1() instead of idefloppy_issue_pc()
so the Status Register and the Interrupt Reason Register
are checked first.

Cc: Borislav Petkov <petkovbb@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>