ASoC: samsung: ASoC: samsung: Fix IISMOD setting in i2s_set_sysclk()

In the i2s_set_sysclk() callback we are currently clearing all bits
of the IISMOD register in i2s_set_sysclk. It's due to an incorrect
mask used for the AND operation which is introduced in commit
a5a56871 (ASoC: samsung:
add support for exynos7 I2S controller) and also adds the missing
break statement.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Padmavathi Venna <padma.v@samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>