pcmcia: remove long deprecated pcmcia_request_exclusive_irq() function

This function was created as a deprecated fallback case back in 2010 by
commit eb14120f ("pcmcia: re-work pcmcia_request_irq()") for legacy
cases.

Actual in-kernel users haven't been around for a long while.  The last
in-kernel user was apparently removed four years ago by commit
5f5316fc

 ("am2150: Update nmclan_cs.c to use update PCMCIA API").

Just remove it entirely.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>