mmc: renesas_sdhi: document version of RZ/A1 instance

We don't use this new define yet, but it is helpful to document which
versions we know of.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Chris Brandt <Chris.Brandt@renesas.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/renesas_sdhi_core.c

@@ -40,6 +40,7 @@
 #define EXT_ACC           0xe4
 
 #define SDHI_VER_GEN2_SDR50	0x490c
+#define SDHI_VER_RZ_A1		0x820b
 /* very old datasheets said 0x490c for SDR104, too. They are wrong! */
 #define SDHI_VER_GEN2_SDR104	0xcb0d
 #define SDHI_VER_GEN3_SD	0xcc10