coresight: etm4x: Fix width of CCITMIN field

CCITMIN is a 12 bit field and doesn't fit in a u8, so extend it to u16.
This probably wasn't an issue previously because values higher than 255
never occurred.

But since commit 4aff040b ("coresight: etm: Override TRCIDR3.CCITMIN
on errata affected cpus"), a comparison with 256 was done to enable the
errata, generating the following W=1 build error:

  coresight-etm4x-core.c:1188:24: error: result of comparison of
  constant 256 with expression of type 'u8' (aka 'unsigned char') is
  always false [-Werror,-Wtautological-constant-out-of-range-compare]

   if (drvdata->ccitmin == 256)

Cc: stable@vger.kernel.org
Fixes: 2e1cdfe1 ("coresight-etm4x: Adding CoreSight ETM4x driver")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202310302043.as36UFED-lkp@intel.com/Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: James Clark <james.clark@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20231101115206.70810-1-james.clark@arm.com

drivers/hwtracing/coresight/coresight-etm4x.h

@@ -1036,7 +1036,7 @@ struct etmv4_drvdata {
 	u8				ctxid_size;
 	u8				vmid_size;
 	u8				ccsize;
-	u8				ccitmin;
+	u16				ccitmin;
 	u8				s_ex_level;
 	u8				ns_ex_level;
 	u8				q_support;