drivers/rtc/rtc-tps65910.c: remove unnecessary include

Currently, driver includes 'pm_runtime.h' which is not used anywhere in
code hence remove this unnecessory inclusion.

Signed-off-by: Manish Badarkhe <badarkhe.manish@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>