hwrng: imx-rngc - use bitfield macros to read rng type

Use the mechanism from bitfield.h to read the rng type field in the
version_id register. This makes the code a tiny bit simpler.
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/char/hw_random/imx-rngc.c

@@ -27,7 +27,7 @@
 #define RNGC_FIFO			0x0014
 
 /* the fields in the ver id register */
-#define RNGC_TYPE_SHIFT		28
+#define RNG_TYPE			GENMASK(31, 28)
 #define RNGC_VER_MAJ_SHIFT		8
 
 /* the rng_type field */
@@ -251,7 +251,7 @@ static int imx_rngc_probe(struct platform_device *pdev)
 		return irq;
 
 	ver_id = readl(rngc->base + RNGC_VER_ID);
-	rng_type = ver_id >> RNGC_TYPE_SHIFT;
+	rng_type = FIELD_GET(RNG_TYPE, ver_id);
 	/*
 	 * This driver supports only RNGC and RNGB. (There's a different
 	 * driver for RNGA.)