Add DBG_PC_INTR debug level and use it to always log debug info
in idetape_pc_intr() if debugging is enabled.

While at it:

* Use drive->name instead of tape->name.

* Log device name with "DMA finished" message.

This is a preparation for adding generic ide_pc_intr() helper.

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