Arm: Fix ldrd offset range [PR115153]

The valid offset range of LDRD in arm_legitimate_index_p is increased to
-1024..1020 if NEON is enabled since VALID_NEON_DREG_MODE includes DImode.
Fix this by moving the LDRD check earlier.

gcc:
	PR target/115153
	* config/arm/arm.cc (arm_legitimate_index_p): Move LDRD case before
	NEON.
	(thumb2_legitimate_index_p): Update comments.
	(output_move_neon): Use DFmode for vldr/vstr and non-checking
	adjust_address.

gcc/testsuite:
	PR target/115153
	* gcc.target/arm/pr115153.c: Add new test.
	* lib/target-supports.exp: Add arm_arch_v7ve_neon target support.