clocksource/drivers/imx-tpm: Mark two variable with __ro_after_init

counter_width and timer_base will not be updated after init, so mark
as __ro_after_init.
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/20211214120737.1611955-4-peng.fan@oss.nxp.comSigned-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

drivers/clocksource/timer-imx-tpm.c

@@ -32,8 +32,8 @@
 #define TPM_C0SC_CHF_MASK		(0x1 << 7)
 #define TPM_C0V				0x24
 
-static int counter_width;
-static void __iomem *timer_base;
+static int counter_width __ro_after_init;
+static void __iomem *timer_base __ro_after_init;
 
 static inline void tpm_timer_disable(void)
 {