ppc: Make hbrev table const

Lookup table 'hbrev' is never written to, so add a 'const' qualifier.
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAndreas Färber <afaerber@suse.de>
Signed-off-by: NAlexander Graf <agraf@suse.de>

target-ppc/int_helper.c

@@ -1484,7 +1484,7 @@ VUPK(lsh, s32, s16, UPKLO)
 /*****************************************************************************/
 /* SPE extension helpers */
 /* Use a table to make this quicker */
-static uint8_t hbrev[16] = {
+static const uint8_t hbrev[16] = {
     0x0, 0x8, 0x4, 0xC, 0x2, 0xA, 0x6, 0xE,
     0x1, 0x9, 0x5, 0xD, 0x3, 0xB, 0x7, 0xF,
 };