When editing a mode page on a tape drive, do not clear the device
specific parameter.

Tape drives include write protect (WP), Buffered Mode and Speed
settings in the device-specific parameter.  Clearing this
parameter on a mode select can have the effect of turning off
write protect or buffered mode, or changing the speed setting of
the tape drive.

Disks report DPO/FUA support via the device specific parameter
for MODE SENSE, but the bit is reserved for MODE SELECT.  So we
clear this for disks (and other non-tape devices) to avoid
potential errors from the target device.

sbin/camcontrol/modeedit.c:
	Clear the device-specific parameter in the mode page
	header if we're not operating on a tape drive.