i2c: riic: Use GENMASK() macro for bitmask definitions

Replace raw bitmask values with the `GENMASK()` macro in the `i2c-riic`
driver to improve readability and maintain consistency.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

drivers/i2c/busses/i2c-riic.c

@@ -56,7 +56,7 @@
 #define ICCR2_RS	BIT(2)
 #define ICCR2_ST	BIT(1)
 
-#define ICMR1_CKS_MASK	0x70
+#define ICMR1_CKS_MASK	GENMASK(6, 4)
 #define ICMR1_BCWP	BIT(3)
 #define ICMR1_CKS(_x)	((((_x) << 4) & ICMR1_CKS_MASK) | ICMR1_BCWP)
 
@@ -74,7 +74,7 @@
 
 #define ICSR2_NACKF	BIT(4)
 
-#define ICBR_RESERVED	0xe0 /* Should be 1 on writes */
+#define ICBR_RESERVED	GENMASK(7, 5) /* Should be 1 on writes */
 
 #define RIIC_INIT_MSG	-1