s390/irq,nmi: Include <asm/vtime.h> header directly

update_timer_sys() and update_timer_mcck() are inlines used for
CPU time accounting from the interrupt and machine-check handlers.
These routines are specific to s390 architecture, but included
via <linux/vtime.h> header implicitly. Avoid the extra loop and
include <asm/vtime.h> header directly.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lore.kernel.org/r/3fb696637c0eb7e9d6ffd6cbf9e647d7c5986b3d.1712760275.git.agordeev@linux.ibm.com