By intel spec

|9B DD /7| FSTSW m2byte| Valid Valid Store FPU status word at m2byteafter checking for pending unmasked floating-point exceptions.|
|9B DF E0| FSTSW AX| Valid Valid Store FPU status word in AX register after checking for pending unmasked floating-point exceptions.|
|DD /7 |FNSTSW *m2byte| Valid Valid Store FPU status word at m2bytewithout checking for pending unmasked floating-point exceptions.|
|DF E0 |FNSTSW *AX| Valid Valid Store FPU status word in AX register without checking for pending unmasked floating-point exceptions|

m2byte is word register, and therefor instruction operand need to be change from f32mem to i16mem.

Differential Revision: http://reviews.llvm.org/D14953

llvm-svn: 254512