serial/imx: get rid of the uses of cpu_is_mx1()

The patch removes all the uses of cpu_is_mx1().  Instead, it uses
the .id_table of platform_driver to distinguish the uart device type,
IMX1_UART and IMX21_UART.  The IMX21_UART type runs on all i.mx
except i.mx1.

A couple of !cpu_is_mx1 logic gets turned into is_imx21_uart,
as the codes wrapped there are really IMX21 type uart specific.

It also removes macro MX1_UCR3_REF25 and MX1_UCR3_REF30 which are
not used anywhere.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
diff --git a/arch/arm/mach-imx/clock-imx21.c b/arch/arm/mach-imx/clock-imx21.c
index bf30a8c..ee15d8c 100644
--- a/arch/arm/mach-imx/clock-imx21.c
+++ b/arch/arm/mach-imx/clock-imx21.c
@@ -1162,10 +1162,10 @@
 	_REGISTER_CLOCK(NULL, "perclk3", per_clk[2])
 	_REGISTER_CLOCK(NULL, "perclk4", per_clk[3])
 	_REGISTER_CLOCK(NULL, "clko", clko_clk)
-	_REGISTER_CLOCK("imx-uart.0", NULL, uart_clk[0])
-	_REGISTER_CLOCK("imx-uart.1", NULL, uart_clk[1])
-	_REGISTER_CLOCK("imx-uart.2", NULL, uart_clk[2])
-	_REGISTER_CLOCK("imx-uart.3", NULL, uart_clk[3])
+	_REGISTER_CLOCK("imx21-uart.0", NULL, uart_clk[0])
+	_REGISTER_CLOCK("imx21-uart.1", NULL, uart_clk[1])
+	_REGISTER_CLOCK("imx21-uart.2", NULL, uart_clk[2])
+	_REGISTER_CLOCK("imx21-uart.3", NULL, uart_clk[3])
 	_REGISTER_CLOCK(NULL, "gpt1", gpt_clk[0])
 	_REGISTER_CLOCK(NULL, "gpt1", gpt_clk[1])
 	_REGISTER_CLOCK(NULL, "gpt1", gpt_clk[2])