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>
diff --git a/drivers/st/bsec/bsec.c b/drivers/st/bsec/bsec.c
index aaecf1f..b3c15ee 100644
--- a/drivers/st/bsec/bsec.c
+++ b/drivers/st/bsec/bsec.c
@@ -32,20 +32,14 @@
 
 static void bsec_lock(void)
 {
-	const uint32_t mask = SCTLR_M_BIT | SCTLR_C_BIT;
-
-	/* Lock is currently required only when MMU and cache are enabled */
-	if ((read_sctlr() & mask) == mask) {
+	if (stm32mp_lock_available()) {
 		spin_lock(&bsec_spinlock);
 	}
 }
 
 static void bsec_unlock(void)
 {
-	const uint32_t mask = SCTLR_M_BIT | SCTLR_C_BIT;
-
-	/* Unlock is required only when MMU and cache are enabled */
-	if ((read_sctlr() & mask) == mask) {
+	if (stm32mp_lock_available()) {
 		spin_unlock(&bsec_spinlock);
 	}
 }