Fixed incorrect CORE-V hwlp masks and error messages. Added xcorevhwlp extension.

gas/ChangeLog.COREV:

	* config/tc-riscv.c: Fixed issue arising from incorrect CORE-V
        hardware loop masks and added support for xcorevhwlp.

gas/testsuite/ChangeLog.COREV:

        * gas/riscv/cv-hwloop-01.d: Changed march option to xcorehwlp.
        * gas/riscv/cv-hwloop-02.d: Likewise.
        * gas/riscv/cv-hwloop-03.d: Likewise.
        * gas/riscv/cv-hwloop-04.d: Likewise.
        * gas/riscv/cv-hwloop-05.d: Likewise.
        * gas/riscv/cv-hwloop-06.d: Likewise.
        * gas/riscv/cv-hwloop-07.d: Likewise.
        * gas/riscv/cv-hwloop-08.d: Likewise.
        * gas/riscv/cv-hwloop-count.d: Likewise.
        * gas/riscv/cv-hwloop-counti.d: Likewise.
        * gas/riscv/cv-hwloop-endi.d: Likewise.
        * gas/riscv/cv-hwloop-setup.d: Likewise.
        * gas/riscv/cv-hwloop-setupi.d: Likewise.
        * gas/riscv/cv-hwloop-starti.d: Likewise.
        * gas/riscv/cv-hwloop-09.d: Likewise.
        * gas/riscv/cv-hwloop-10.d: Likewise.
        * gas/riscv/cv-hwloop-11.d: Added new test.
        * gas/riscv/cv-hwloop-11.l: Likewise.
        * gas/riscv/cv-hwloop-11.s: Likewise.
        * gas/riscv/cv-hwloop-12.d: Likewise.
        * gas/riscv/cv-hwloop-12.l: Likewise.
        * gas/riscv/cv-hwloop-12.s: Likewise.
        * gas/riscv/cv-hwloop-13.d: Likewise.
        * gas/riscv/cv-hwloop-13.l: Likewise.
        * gas/riscv/cv-hwloop-13.s: Likewise.
        * gas/riscv/cv-hwloop-14.d: Likewise.
        * gas/riscv/cv-hwloop-14.l: Likewise.
        * gas/riscv/cv-hwloop-14.s: Likewise.
        * gas/riscv/cv-hwloop-15.d: Likewise.
        * gas/riscv/cv-hwloop-15.l: Likewise.
        * gas/riscv/cv-hwloop-15.s: Likewise.
        * gas/riscv/cv-march-rv32i-xcorev.s: Added test for march option.
        * gas/riscv/cv-march-rv32i-xcorev.d: Likewise.

include/ChangeLog.COREV:

	* opcode/riscv-opc.h: Fixed incorrect masks for CORE-V hardware loop
        instructions.
	* opcode/riscv.h: Added support for xcorevhwlp.

ld/testsuite/ChangeLog.COREV:

	* ld-riscv-elf/cv-hwloop-starti.d: Changed march option to xcorevhwlp.
        * ld-riscv-elf/cv-hwloop-endi.d: Likewise.
        * ld-riscv-elf/cv-hwloop-setup.d: Likewise.
        * ld-riscv-elf/cv-hwloop-setupi.d: Likewise.

opcodes/ChangeLog.COREV:

	* riscv-opc.c: Added support for corevhwlp.

Signed-off-by: Mary Bennett <mary.bennett@embecosm.com>