MIPS: cp1emu: Fix ISA restrictions for cop1x_op instructions

MIPS: cp1emu: Fix ISA restrictions for cop1x_op instructions

Commit 08a07904e1828 ("MIPS: math-emu: Remove most ifdefery") removed
the #ifdef ISA conditions and switched to runtime detection. However,
according to the instruction set manual, the cop1x_op instructions are
available in >=MIPS32r2 as well. This fixes a problem on MIPS32r2
with the ntpd package which failed to execute with a SIGILL exit code due
to the fact that a madd.d instruction was not being emulated.

Signed-off-by: Markos Chandras <[email protected]>
Fixes: 08a07904e1828 ("MIPS: math-emu: Remove most ifdefery")
Cc: <[email protected]> # v3.16+
Cc: [email protected]
Reviewed-by: Paul Burton <[email protected]>
Reviewed-by: James Hogan <[email protected]>
Cc: Markos Chandras <[email protected]>
Patchwork: https://patchwork.linux-mips.org/patch/8173/
Signed-off-by: Ralf Baechle <[email protected]>