[PATCH] ads7846 build fix

sparc32:

drivers/input/touchscreen/ads7846.c: In function `ads7846_read12_ser':
drivers/input/touchscreen/ads7846.c:206: warning: implicit declaration of function `disable_irq'
drivers/input/touchscreen/ads7846.c:208: warning: implicit declaration of function `enable_irq'

Cc: Dmitry Torokhov <dtor_core@ameritech.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>