rtc: m41t80: do not use rtc_valid_tm in m41t80_rtc_read_alarm

rtc: m41t80: do not use rtc_valid_tm in m41t80_rtc_read_alarm

Commit b485fe5ea ("rtc/m41t80: use rtc_valid_tm() to check returned tm")
added rtc_valid_tm to m41t80_rtc_read_alarm() but it was wrong while the
t->time does not contain complete date/time.

This patch also fixes a warning:
warning: passing argument 1 of 'rtc_valid_tm' from incompatible pointer type

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: Wan ZongShun <mcuos.com@gmail.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>