MIPS: Add FPU emulator counter for emulated delay slots.

Delay slot emulation in the FPU emulator is the only kernel user of an
executable stack, it is also very slow.  Add a counter so we can see
how many of these emulations are done.

Signed-off-by: David Daney <david.daney@cavium.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8634/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --cc arch/mips/include/asm/fpu_emulator.h
Simple merge

diff --cc arch/mips/math-emu/dsemul.c
Simple merge

diff --cc arch/mips/math-emu/me-debugfs.c
Simple merge