[GAS, Arm] PR24559: Fix pseudo load-operations for Armv8-M Baseline

[GAS, Arm] PR24559: Fix pseudo load-operations for Armv8-M Baseline

gas/ChangeLog:
2019-05-21  Andre Vieira  <andre.simoesdiasvieira@arm.com>

	Backport from mainline
	2019-05-21  Andre Vieira  <andre.simoesdiasvieira@arm.com>

	PR24559
	* config/tc-arm.c (move_or_literal_pool): Set size_req to 0 for MOVW
	replacement.
	* testsuite/gas/arm/load-pseudo.s: New test input.
	* testsuite/gas/arm/m0-load-pseudo.d: New test.
	* testsuite/gas/arm/m23-load-pseudo.d: New test.
	* testsuite/gas/arm/m33-load-pseudo.d: New test.