RISC-V: Add 'Sscofpmf' extension with its CSRs

RISC-V: Add 'Sscofpmf' extension with its CSRs

This commit adds Count Overflow and Mode-Based Filtering Extension
(Sscofpmf) and its CSRs.

bfd/ChangeLog:

	* elfxx-riscv.c (riscv_supported_std_s_ext): Add 'Sscofpmf'
	extension to valid 'S' extension list.

gas/ChangeLog:

	* config/tc-riscv.c (enum riscv_csr_class): Add CSR classes for
	'Sscofpmf' extension. (riscv_csr_address): Add handling for new
	CSR classes.
	* testsuite/gas/riscv/csr-dw-regnums.s: Add new CSRs.
	* testsuite/gas/riscv/csr-dw-regnums.d: Likewise.
	* testsuite/gas/riscv/csr.s: Add new CSRs.
	* testsuite/gas/riscv/csr-version-1p9p1.d: Likewise.
	* testsuite/gas/riscv/csr-version-1p9p1.l: Likewise.
	* testsuite/gas/riscv/csr-version-1p10.d: Likewise.
	* testsuite/gas/riscv/csr-version-1p10.l: Likewise.
	* testsuite/gas/riscv/csr-version-1p11.d: Likewise.
	* testsuite/gas/riscv/csr-version-1p11.l: Likewise.
	* testsuite/gas/riscv/csr-version-1p12.d: Likewise.
	* testsuite/gas/riscv/csr-version-1p12.l: Likewise.

include/ChangeLog:

	* opcode/riscv-opc.h (CSR_SCOUNTOVF, CSR_MHPMEVENT3H,
	CSR_MHPMEVENT4H, CSR_MHPMEVENT5H, CSR_MHPMEVENT6H,
	CSR_MHPMEVENT7H, CSR_MHPMEVENT8H, CSR_MHPMEVENT9H,
	CSR_MHPMEVENT10H, CSR_MHPMEVENT11H, CSR_MHPMEVENT12H,
	CSR_MHPMEVENT13H, CSR_MHPMEVENT14H, CSR_MHPMEVENT15H,
	CSR_MHPMEVENT16H, CSR_MHPMEVENT17H, CSR_MHPMEVENT18H,
	CSR_MHPMEVENT19H, CSR_MHPMEVENT20H, CSR_MHPMEVENT21H,
	CSR_MHPMEVENT22H, CSR_MHPMEVENT23H, CSR_MHPMEVENT24H,
	CSR_MHPMEVENT25H, CSR_MHPMEVENT26H, CSR_MHPMEVENT27H,
	CSR_MHPMEVENT28H, CSR_MHPMEVENT29H, CSR_MHPMEVENT30H,
	CSR_MHPMEVENT31H): New CSR macros.