target-arm: Fix incorrect type for value argument to write_raw_cp_reg

The write_raw_cp_reg's value argument should be a uint64_t, since
that's what all its callers hand it and what all the functions it
calls take. A (harmless) typo meant we were accidentally declaring
it as int64_t.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>

target-arm/helper.c

@@ -141,7 +141,7 @@ static uint64_t read_raw_cp_reg(CPUARMState *env, const ARMCPRegInfo *ri)
 }
 
 static void write_raw_cp_reg(CPUARMState *env, const ARMCPRegInfo *ri,
-                             int64_t v)
+                             uint64_t v)
 {
     /* Raw write of a coprocessor register (as needed for migration, etc).
      * Note that constant registers are treated as write-ignored; the