MIPS: Correct ISA masking in FPU feature determination

MIPS: Correct ISA masking in FPU feature determination

Correct an ISA level determination problem introduced with 8b8aa636
[MIPS: kernel: cpu-probe.c: Add support for MIPS R6], reverting explicit
masking against individual `MIPS_CPU_ISA_*' macros in FPU feature
determination.

Feature macros such as `cpu_has_mips_r' cannot be used here, because
they operate on CPU #0 and we want to refer to the current CPU instead.
They cannot be used for masking against the current CPU either because
they mask against CPU #0 too, e.g.:

# define cpu_has_mips32r1	(cpu_data[0].isa_level & MIPS_CPU_ISA_M32R1)

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9706/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>