efi: include irq.h to fix compile error in runtime.c

efi: include irq.h to fix compile error in runtime.c

runtime.c: In function 'efi_rs_enter':
runtime.c:45:5: error: implicit declaration of function 'irq_enter'
[-Werror=implicit-function-declaration]
runtime.c:45:5: error: nested extern declaration of 'irq_enter'
[-Werror=nested-externs]
runtime.c: In function 'efi_rs_leave':
runtime.c:75:5: error: implicit declaration of function 'irq_exit'
[-Werror=implicit-function-declaration]
runtime.c:75:5: error: nested extern declaration of 'irq_exit'
[-Werror=nested-externs]

Signed-off-by: Olaf Hering <olaf@aepfle.de>