s390/fpu: fix VLGV macro

The VLGV macro generates the VLGV instruction and has a vr parameter which
correlates to the V3 vector register field of the instruction (bits 12-15).
Due to its position in the VRS-c instruction format of the VLGV
instruction, this field correlates to the second bit of the RXB byte of the
instruction (see Principles of Operation, Chapter "Vector Overview and
Support Instructions").

Within the VLGV macro the MRXBOPC macro is used to generate the RXB field
of the instruction. The usage of the MRXBOPC macro is incorrect, since the
vector register number is passed as third parameter (which correlates to
the first bit of the RXB byte), while it should be passed as fourth
parameter (second bit of the RXB byte). In result an incorrect instruction
would be generated if the VLGV macro would be used for vector register
numbers larger than 15.

Fix this and pass the vector register number as fourth parameter.

Currently there are no users within the kernel which use the macro in a way
that broken code would be generated.
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

arch/s390/include/asm/vx-insn-asm.h

@@ -350,7 +350,7 @@
 	VX_NUM	v3, \vr
 	.word	0xE700 | (r1 << 4) | (v3&15)
 	.word	(b2 << 12) | (\disp)
-	MRXBOPC	\m, 0x21, v3
+	MRXBOPC	\m, 0x21, 0, v3
 .endm
 .macro	VLGVB	gr, vr, disp, base="%r0"
 	VLGV	\gr, \vr, \disp, \base, 0