drivers/rtc/rtc-tps65910.c: fix incorrect return value on error

drivers/rtc/rtc-tps65910.c: fix incorrect return value on error

'ret' was not initialized to correct error value before returning.  Since
'irq' is also being tested for 0, we cannot return irq itself as it means
function is success even though we are returning before completing the
probe.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Acked-by: Venu Byravarasu <vbyravarasu@nvidia.com>
Cc: Chiwoong Byun <woong.byun@samsung.com>
Cc: Jonghwa Lee <jonghwa3.lee@samsung.com>
Cc: Laxman dewangan <ldewangan@nvidia.com>
Cc: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>