RISC-V: Update Zihintpause extension version

Because ratified Zihintpause extension has a version number of 2.0
(not 1.0), we should update the number.

bfd/ChangeLog:

	* elfxx-riscv.c (riscv_supported_std_z_ext): Update version
	number of Zihintpause extension.
1 file changed