drivers/rtc/rtc-pl031.c: remove RTC timer interrupt handling

Remove RTT interrupt handling, since PIE mode interrupts are now better
emulated in generic code via an hrtimer we have no need for this, and
there is no codepath in the driver that enables these periodic interrupts
anyway.

Signed-off-by: Rajkumar Kasirajan <rajkumar.kasirajan@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Cc: Mattias Wallin <mattias.wallin@stericsson.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>