perf/imx_ddr: Fix undefined behavior due to shift overflowing the constant

Fix:

  In file included from <command-line>:0:0:
  In function ‘ddr_perf_counter_enable’,
      inlined from ‘ddr_perf_irq_handler’ at drivers/perf/fsl_imx8_ddr_perf.c:651:2:
  ././include/linux/compiler_types.h:352:38: error: call to ‘__compiletime_assert_729’ \
	declared with attribute error: FIELD_PREP: mask is not constant
    _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
...

See https://lore.kernel.org/r/YkwQ6%2BtIH8GQpuct@zn.tnic for the gory
details as to why it triggers with older gccs only.
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Frank Li <Frank.li@nxp.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: linux-arm-kernel@lists.infradead.org
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20220405151517.29753-10-bp@alien8.deSigned-off-by: Will Deacon <will@kernel.org>

drivers/perf/fsl_imx8_ddr_perf.c

@@ -29,7 +29,7 @@
 #define CNTL_OVER_MASK		0xFFFFFFFE
 
 #define CNTL_CSV_SHIFT		24
-#define CNTL_CSV_MASK		(0xFF << CNTL_CSV_SHIFT)
+#define CNTL_CSV_MASK		(0xFFU << CNTL_CSV_SHIFT)
 
 #define EVENT_CYCLES_ID		0
 #define EVENT_CYCLES_COUNTER	0