[ARM] rtc-pcf8583: Final fixes for this RTC on RiscPC

Replace the I2C bus address, as per drivers/acorn/char/pcf8583.c.

Also, since this driver also contains Acorn RiscPC specific code
for obtaining the current year from the SRAM (and updating the
platform specific checksum when writing new data back) this is
NOT a platform independent driver.

Document it as such, and update the dependencies to reflect this
fact.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/drivers/rtc/rtc-pcf8583.c b/drivers/rtc/rtc-pcf8583.c
index a33a2d6..d48b033 100644
--- a/drivers/rtc/rtc-pcf8583.c
+++ b/drivers/rtc/rtc-pcf8583.c
@@ -40,7 +40,7 @@
 #define CTRL_ALARM	0x02
 #define CTRL_TIMER	0x01
 
-static unsigned short normal_i2c[] = { I2C_CLIENT_END };
+static unsigned short normal_i2c[] = { 0x50, I2C_CLIENT_END };
 
 /* Module parameters */
 I2C_CLIENT_INSMOD;