powerpc/signal: Fix confusing header documentation in sigcontext.h

Commit ce48b210 "powerpc: Add VSX context save/restore, ptrace and
signal support" expanded the 'vmx_reserve' array element to contain 101
double words, but the comment block above was not updated.

Also reorder the constants in the array size declaration to reflect the
logic mentioned in the comment block above. This change helps in
explaining how the HW registers are represented in the array. But no
functional change.
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
[mpe: Reworded change log and added whitespace around +'s]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/uapi/asm/sigcontext.h

@@ -28,7 +28,7 @@ struct sigcontext {
 /*
  * To maintain compatibility with current implementations the sigcontext is
  * extended by appending a pointer (v_regs) to a quadword type (elf_vrreg_t)
- * followed by an unstructured (vmx_reserve) field of 69 doublewords.  This
+ * followed by an unstructured (vmx_reserve) field of 101 doublewords. This
  * allows the array of vector registers to be quadword aligned independent of
  * the alignment of the containing sigcontext or ucontext. It is the
  * responsibility of the code setting the sigcontext to set this pointer to
@@ -80,7 +80,7 @@ struct sigcontext {
  * registers and vscr/vrsave.
  */
 	elf_vrreg_t	__user *v_regs;
-	long		vmx_reserve[ELF_NVRREG+ELF_NVRREG+32+1];
+	long		vmx_reserve[ELF_NVRREG + ELF_NVRREG + 1 + 32];
 #endif
 };