[COMMON] serial: samsung: Add interrupt masking before enable the channel & remove...

[COMMON] serial: samsung: Add interrupt masking before enable the channel & remove duplicaed function call.

1. If the UART channel is located in non-alive block, SFR values go to
the reset value after the system power mode. So the interrupt
should be masked before enabling the channel otherwise Tx interrupt
will be occurred without any purpose.

2. UART channel reset is called twice when resume sequence, so we
decided to remove one of reset function call.

Change-Id: Ie84c51b0c97c572d48d302b43ec3ee64ee5ea597
Signed-off-by: Kyungwoo Kang <kwoo.kang@samsung.com>