target/riscv: fix inverted checks for ext_zb[abcs]

target/riscv: fix inverted checks for ext_zb[abcs]

While changing to the use of cfg_ptr, the conditions for REQUIRE_ZB[ABCS]
inadvertently became inverted and slipped through the initial testing (which
used RV64GC_XVentanaCondOps as a target).
This fixes the regression.

Tested against SPEC2017 w/ GCC 12 (prerelease) for RV64GC_zba_zbb_zbc_zbs.

Fixes: f2a32bec8f0da99 ("target/riscv: access cfg structure through DisasContext")
Signed-off-by: Philipp Tomsich <philipp.tomsich@vrull.eu>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20220203153946.2676353-1-philipp.tomsich@vrull.eu>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>