Revert "[ARM] pxa: introduce cpu_is_pxa26x()"

This reverts commit da1a3dc0.

The originally proposed way in the above commit is incorrect. And
there is no easy way to distinguish between pxa25x and pxa26x at
run-time.
Signed-off-by: Eric Miao <eric.miao@marvell.com>

arch/arm/mach-pxa/include/mach/hardware.h

@@ -204,8 +204,6 @@
 		__cpu_is_pxa25x(read_cpuid_id());	\
 	})
 
-extern int cpu_is_pxa26x(void);
-
 #define cpu_is_pxa27x()					\
 	({						\
 		__cpu_is_pxa27x(read_cpuid_id());	\

arch/arm/mach-pxa/pxa25x.c

@@ -36,12 +36,6 @@
 #include "devices.h"
 #include "clock.h"
 
-int cpu_is_pxa26x(void)
-{
-	return cpu_is_pxa250() && ((BOOT_DEF & 0x8) == 0);
-}
-EXPORT_SYMBOL_GPL(cpu_is_pxa26x);
-
 /*
  * Various clock factors driven by the CCCR register.
  */
@@ -356,7 +350,7 @@ static int __init pxa25x_init(void)
 	}
 
 	/* Only add HWUART for PXA255/26x; PXA210/250 do not have it. */
-	if (cpu_is_pxa255() || cpu_is_pxa26x()) {
+	if (cpu_is_pxa255()) {
 		clks_register(&pxa25x_hwuart_clk, 1);
 		ret = platform_device_register(&pxa_device_hwuart);
 	}