arm: [MVE intrinsics] rework sqshll srshrl uqshll urshrl

arm: [MVE intrinsics] rework sqshll srshrl uqshll urshrl

Implement sqshll, srshrl, uqshll and urshrl using the new MVE builtins
framework.

gcc/ChangeLog:
	* config/arm/arm-mve-builtins-base.cc (enum which_scalar_shift):
	Add ss_SQSHLL, ss_SRSHRL, ss_UQSHLL, ss_URSHRL.
	(mve_function_scalar_shift): Add support for ss_SQSHLL, ss_SRSHRL,
	ss_UQSHLL, ss_URSHRL.
	* config/arm/arm-mve-builtins-base.def (sqshll, srshrl, uqshll)
	(urshrl): New.
	* config/arm/arm-mve-builtins-base.h (sqshll, srshrl, uqshll)
	(urshrl): New.
	* config/arm/arm-mve-builtins-shapes.cc (scalar_s64_shift_imm)
	(scalar_u64_shift_imm): New.
	* config/arm/arm-mve-builtins-shapes.h (scalar_s64_shift_imm)
	(scalar_u64_shift_imm): New.
	* config/arm/arm_mve.h (sqshll): Delete.
	(srshrl): Delete.
	(uqshll): Delete.
	(urshrl): Delete.
	(__arm_uqshll): Delete.
	(__arm_urshrl): Delete.
	(__arm_srshrl): Delete.
	(__arm_sqshll): Delete.

gcc/testsuite/ChangeLog:
	* gcc.target/arm/mve/intrinsics/sqshll_check_shift.c: New test.
	* gcc.target/arm/mve/intrinsics/srshrl_check_shift.c: New test.
	* gcc.target/arm/mve/intrinsics/uqshll_check_shift.c: New test.
	* gcc.target/arm/mve/intrinsics/urshrl_check_shift.c: New test.