arch: arm: cortex_r: Enable Thumb2 instruction set support

The ARMv7-R architecture supports both Thumb-2 (T32) and ARM (A32)
instruction sets.

This commit selects the `ISA_THUMB2` symbol to indicate that the
ARMv7-R architecture supports the Thumb-2 instruction set, which can
be enabled by selecting the `COMPILER_ISA_THUMB2` symbol.

Signed-off-by: Stephanos Ioannidis <[email protected]>

Author: stephanosio

arch/arm/core/aarch32/cortex_r/Kconfig

@@ -33,6 +33,7 @@ config ARMV7_R
 	bool
 	select ATOMIC_OPERATIONS_BUILTIN
 	select ISA_ARM
+	select ISA_THUMB2
 	help
 	  This option signifies the use of an ARMv7-R processor
 	  implementation.