LoongArch: Use iorn and andn standard pattern names.

LoongArch: Use iorn and andn standard pattern names.

R15-1890 introduced new optabs iorc and andc, and its corresponding
internal functions BIT_{ANDC,IORC}, and if targets defines such optabs
for vector modes.  And in r15-2258 the iorc and andc were renamed to
iorn and andn.
So we changed the andn and iorn implementation templates to the standard
template names.

gcc/ChangeLog:

	* config/loongarch/lasx.md (xvandn<mode>3): Rename to ...
	(andn<mode>3): This.
	(xvorn<mode>3): Rename to ...
	(iorn<mode>3): This.
	* config/loongarch/loongarch-builtins.cc
	(CODE_FOR_lsx_vandn_v): Defined as the modified name.
	(CODE_FOR_lsx_vorn_v): Likewise.
	(CODE_FOR_lasx_xvandn_v): Likewise.
	(CODE_FOR_lasx_xvorn_v): Likewise.
	(loongarch_expand_builtin_insn): When the builtin function to be
	called is __builtin_lasx_xvandn or __builtin_lsx_vandn, swap the
	two operands.
	* config/loongarch/loongarch.md (<optab>n<mode>): Rename to ...
	(<optab>n<mode>3): This.
	* config/loongarch/lsx.md (vandn<mode>3): Rename to ...
	(andn<mode>3): This.
	(vorn<mode>3): Rename to ...
	(iorn<mode>3): This.

gcc/testsuite/ChangeLog:

	* gcc.target/loongarch/lasx-andn-iorn.c: New test.
	* gcc.target/loongarch/lsx-andn-iorn.c: New test.