drivers/rtc/rtc-vr41xx.c: fix error return code in rtc_probe()

Fix to return -EBUSY in the platform irq get error handling case instead
of 0, as done elsewhere in this function.

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>