[PATCH] RTC: Add rtc_year_days() to calculate tm_yday

RTC: Add exported function rtc_year_days() to calculate the tm_yday value.

Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>