stm32mp1: use a common function to check spinlock is available

stm32mp1: use a common function to check spinlock is available

To use spinlocks, MMU should be enabled, as well as data cache.
A common function is created (moved from clock file).
It is then used whenever a spinlock has to be taken, in BSEC and clock
drivers.

Change-Id: I94baed0114a2061ad71bd5287a91bf7f1c6821f6
Signed-off-by: Yann Gautier <yann.gautier@st.com>