nommu: Do not override the CP15 control reg value returned from initfunc

The patch removes the "mrc" instruction in head-nommu.S overriding the
r0 register containing the value to be written in the CP15 system
control register.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm/kernel/head-nommu.S

@@ -61,7 +61,10 @@ ENDPROC(stext)
  */
 __after_proc_init:
 #ifdef CONFIG_CPU_CP15
-	mrc	p15, 0, r0, c1, c0, 0		@ read control reg
+	/*
+	 * CP15 system control register value returned in r0 from
+	 * the CPU init function.
+	 */
 #ifdef CONFIG_ALIGNMENT_TRAP
 	orr	r0, r0, #CR_A
 #else