MIPS: asmmacro: Ensure 64-bit FP registers are used with MSA

This silences warnings like the following one when building with the
latest binutils:

arch/mips/kernel/genex.S: Assembler messages:
arch/mips/kernel/genex.S:438: Warning: the `msa' extension requires 64-bit FPRs

[ralf@linux-mips.org: Markos says binutils 2.25 and some 2.24 snapshots
are affected.]
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9745/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/asmmacro.h

@@ -211,9 +211,13 @@
 	.endm
 
 #ifdef TOOLCHAIN_SUPPORTS_MSA
+/* preprocessor replaces the fp in ".set fp=64" with $30 otherwise */
+#undef fp
+
 	.macro	_cfcmsa	rd, cs
 	.set	push
 	.set	mips32r2
+	.set	fp=64
 	.set	msa
 	cfcmsa	\rd, $\cs
 	.set	pop
@@ -222,6 +226,7 @@
 	.macro	_ctcmsa	cd, rs
 	.set	push
 	.set	mips32r2
+	.set	fp=64
 	.set	msa
 	ctcmsa	$\cd, \rs
 	.set	pop
@@ -230,6 +235,7 @@
 	.macro	ld_d	wd, off, base
 	.set	push
 	.set	mips32r2
+	.set	fp=64
 	.set	msa
 	ld.d	$w\wd, \off(\base)
 	.set	pop
@@ -238,6 +244,7 @@
 	.macro	st_d	wd, off, base
 	.set	push
 	.set	mips32r2
+	.set	fp=64
 	.set	msa
 	st.d	$w\wd, \off(\base)
 	.set	pop
@@ -246,6 +253,7 @@
 	.macro	copy_u_w	ws, n
 	.set	push
 	.set	mips32r2
+	.set	fp=64
 	.set	msa
 	copy_u.w $1, $w\ws[\n]
 	.set	pop
@@ -254,6 +262,7 @@
 	.macro	copy_u_d	ws, n
 	.set	push
 	.set	mips64r2
+	.set	fp=64
 	.set	msa
 	copy_u.d $1, $w\ws[\n]
 	.set	pop
@@ -262,6 +271,7 @@
 	.macro	insert_w	wd, n
 	.set	push
 	.set	mips32r2
+	.set	fp=64
 	.set	msa
 	insert.w $w\wd[\n], $1
 	.set	pop
@@ -270,6 +280,7 @@
 	.macro	insert_d	wd, n
 	.set	push
 	.set	mips64r2
+	.set	fp=64
 	.set	msa
 	insert.d $w\wd[\n], $1
 	.set	pop