arch: arm: fix USE_SWITCH for armclang

Fix below issues when trying to build hello world with armclang:
```
Error: L6218E: Undefined symbol z_arm_exc_exit (referred from reset.o).
Error: L6218E: Undefined symbol z_arm_int_exit (referred from reset.o).
Error: L6218E: Undefined symbol z_arm_pendsv (referred from reset.o).
```

Signed-off-by: Sudan Landge <sudan.landge@arm.com>

Author: wearyzen

arch/arm/core/cortex_m/vector_table.h

@@ -47,7 +47,9 @@ GTEXT(z_arm_debug_monitor)
 #else
 #error Unknown ARM architecture
 #endif /* CONFIG_ARMV6_M_ARMV8_M_BASELINE */
+#ifndef CONFIG_USE_SWITCH
 GTEXT(z_arm_pendsv)
+#endif
 GTEXT(z_arm_exc_spurious)
 
 GTEXT(z_prep_c)

include/zephyr/arch/arm/cortex_m/exception.h

@@ -60,7 +60,9 @@
 #define _EXC_PENDSV_PRIO_MASK Z_EXC_PRIO(_EXC_PENDSV_PRIO)
 
 #ifdef _ASMLANGUAGE
+#ifndef CONFIG_USE_SWITCH
 GTEXT(z_arm_exc_exit);
+#endif
 #else
 #include <zephyr/types.h>
 

include/zephyr/arch/arm/irq.h

@@ -37,7 +37,9 @@ extern "C" {
 #define arch_irq_disable                    arm_irq_disable
 #define arch_irq_is_enabled                 arm_irq_is_enabled
 #endif
+#ifndef CONFIG_USE_SWITCH
 GTEXT(z_arm_int_exit);
+#endif
 GTEXT(arch_irq_enable)
 GTEXT(arch_irq_disable)
 GTEXT(arch_irq_is_enabled)