arch: arm: cortex_m: Fix constraint on inline assembly for armv8-m.baseline

`mov` on armv8-m.baseline, when used with an immediate value is limited to
registers `r0` to `r7`. `=r` tells the compiler any register can be used.
`=l` needs to be used instead.

Signed-off-by: Wilfried Chauveau <[email protected]>

Author: ithinuel

include/zephyr/arch/arm/asm_inline_gcc.h

@@ -61,7 +61,15 @@ static ALWAYS_INLINE unsigned int arch_irq_lock(void)
 		"mrs %0, BASEPRI;"
 		"msr BASEPRI_MAX, %1;"
 		"isb;"
-		: "=r"(key), "=r"(tmp)
+		: "=r"(key),
+#if defined(CONFIG_ARMV8_M_BASELINE)
+		/* armv8-m.baseline's mov is limited to registers r0-r7.
+		 * Let the compiler know we have this constraint on tmp.
+		 */
+		"=l"(tmp)
+#else
+		"=r"(tmp)
+#endif
 		: "i"(_EXC_IRQ_DEFAULT_PRIO)
 		: "memory");
 #elif defined(CONFIG_ARMV7_R) || defined(CONFIG_AARCH32_ARMV8_R) \