arch/arm: introduce and use BR2_ARM_CPU_ARMV7M

All ARM cores should select a BR2_ARM_CPU_* option. Currently, the
cortex-m3 does not, which this commit fixes by introducing a
BR2_ARM_CPU_ARMV7M option.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

arch/Config.in.arm

@@ -52,6 +52,9 @@ config BR2_ARM_CPU_ARMV6
 config BR2_ARM_CPU_ARMV7A
 	bool
 
+config BR2_ARM_CPU_ARMV7M
+	bool
+
 choice
 	prompt "Target Architecture Variant"
 	depends on BR2_arm || BR2_armeb
@@ -171,6 +174,7 @@ config BR2_cortex_m3
 	bool "cortex-M3"
 	select BR2_ARM_CPU_HAS_THUMB
 	select BR2_ARM_CPU_HAS_THUMB2
+	select BR2_ARM_CPU_ARMV7M
 config BR2_fa526
 	bool "fa526/626"
 	select BR2_ARM_CPU_HAS_ARM