pcmcia: remove unused IRQ_FIRST_SHARED

Komuro pointed out that IRQ_FIRST_SHARED is not used at all in the
PCMCIA subsystem, so remove it. Also, remove two bogus assignments.

CC: Karsten Keil <keil@b1-systems.de>
CC: netdev@vger.kernel.org
CC: alsa-devel@alsa-project.org
CC: Komuro <komurojun-mbn@nifty.com>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>