[mips] Correct .MIPS.abiflags fp_abi field for -mfpxx and without .module

[dsanders]

Summary

Previously all the test cases set it after initialization with '.module fp=xx'.

[vmedic]

LGTM

lib/Target/Mips/AsmParser/MipsAsmParser.cpp

#undef GET_OPERAND_DIAGNOSTIC_TYPES
   /// True if all of $fcc0 - $fcc7 exist for the current ISA.
   bool hasEightFccRegisters() const { return hasMips4() || hasMips32(); }
 
   bool isGP64bit() const { return STI.getFeatureBits() & Mips::FeatureGP64Bit; }
   bool isFP64bit() const { return STI.getFeatureBits() & Mips::FeatureFP64Bit; }
   bool isABI_N32() const { return STI.getFeatureBits() & Mips::FeatureN32; }
   bool isABI_N64() const { return STI.getFeatureBits() & Mips::FeatureN64; }
   bool isABI_O32() const { return STI.getFeatureBits() & Mips::FeatureO32; }
-  bool isABI_FPXX() const { return false; } // TODO: add check for FeatureXX
+  bool isABI_FPXX() const { return STI.getFeatureBits() & Mips::FeatureFPXX; }
 
   bool useOddSPReg() const {
     return !(STI.getFeatureBits() & Mips::FeatureNoOddSPReg);
   }
 
   bool inMicroMipsMode() const {
     return STI.getFeatureBits() & Mips::FeatureMicroMips;
   }

test/MC/Mips/mips_abi_flags_xx.s

 # RUN: llvm-mc %s -arch=mips -mcpu=mips32 | \
 # RUN:   FileCheck %s -check-prefix=CHECK-ASM
 #
 # RUN: llvm-mc %s -arch=mips -mcpu=mips32 -filetype=obj -o - | \
 # RUN:   llvm-readobj -sections -section-data -section-relocations - | \
 # RUN:     FileCheck %s -check-prefix=CHECK-OBJ
 
+# RUN: llvm-mc /dev/null -arch=mips -mcpu=mips32 -mattr=fpxx -filetype=obj -o - | \
+# RUN:   llvm-readobj -sections -section-data -section-relocations - | \
+# RUN:     FileCheck %s -check-prefix=CHECK-OBJ
+
 # CHECK-ASM: .module fp=xx
 
 # Checking if the Mips.abiflags were correctly emitted.
 # CHECK-OBJ:       Section {
 # CHECK-OBJ:         Index: 5
 # CHECK-OBJ-LABEL:   Name: .MIPS.abiflags (12)
 # CHECK-OBJ:         Type:  (0x7000002A)
 # CHECK-OBJ:          Flags [ (0x2)