ARM64: Insert barriers before Store-Release operations

Some early samples of MSMTHULIUM require that a barrier be
inserted prior to any Store-Release (STLR) operation, for
compliance with ARM memory ordering requirements. Create a
Kconfig option to enable such behavior.

Change-Id: Icc4f38e973b8dd2393f8ec8f1f3ac548630dfc7c
Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>
[abhimany: rename thulium to MSM8996]
Signed-off-by: Abhimanyu Kapur <abhimany@codeaurora.org>