rtc: Make mc13783-rtc driver generic

Rename mc13783-rtc so that it can be used for both MC13783 and MC13892 PMICs.

efikamx board, for example, does use a MC13892 PMIC, but the RTC selection is currently made as:

#define CONFIG_RTC_MC13783

,which is not very obvious.

Let the MC13783 and MC13892 RTC be selected by:

#define CONFIG_RTC_MC13XXX

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Stefano Babic <sbabic@denx.de>
diff --git a/include/configs/efikamx.h b/include/configs/efikamx.h
index b507786..a07c8b5 100644
--- a/include/configs/efikamx.h
+++ b/include/configs/efikamx.h
@@ -132,7 +132,7 @@
 #define CONFIG_FSL_PMIC_CLK		25000000
 #define CONFIG_FSL_PMIC_MODE		(SPI_MODE_0 | SPI_CS_HIGH)
 #define CONFIG_FSL_PMIC_BITLEN	32
-#define CONFIG_RTC_MC13783
+#define CONFIG_RTC_MC13XXX
 #endif
 
 /*