target-tricore: Fix two helper functions (clang warnings)

clang report:

target-tricore/op_helper.c:1247:24: warning:
  taking the absolute value of unsigned type 'uint32_t' (aka 'unsigned int')
  has no effect [-Wabsolute-value]
target-tricore/op_helper.c:1248:25: warning:
  taking the absolute value of unsigned type 'uint32_t' (aka 'unsigned int')
  has no effect [-Wabsolute-value]
target-tricore/op_helper.c:1249:19: warning:
  taking the absolute value of unsigned type 'uint32_t' (aka 'unsigned int')
  has no effect [-Wabsolute-value]
target-tricore/op_helper.c:1297:24: warning:
  taking the absolute value of unsigned type 'uint32_t' (aka 'unsigned int')
  has no effect [-Wabsolute-value]
target-tricore/op_helper.c:1298:25: warning:
  taking the absolute value of unsigned type 'uint32_t' (aka 'unsigned int')
  has no effect [-Wabsolute-value]
target-tricore/op_helper.c:1299:19: warning:
  taking the absolute value of unsigned type 'uint32_t' (aka 'unsigned int')
  has no effect [-Wabsolute-value]

Fix also the divisor which was taken from the wrong register
(thanks to Peter Maydell for this hint).

Cc: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
Signed-off-by: Stefan Weil <sw@weilnetz.de>
Message-Id: <1425739412-8144-1-git-send-email-sw@weilnetz.de>
Signed-off-by: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>