arm1176 cpu_reset() changes for ast2500

[legoater]

The original uboot from the aspeed sdk contains a modification of cpu_reset()
which would need some investigation before submitting the support of the
ast2500 upstream.

  --- a/arch/arm/cpu/arm1176/start.S
  +++ b/arch/arm/cpu/arm1176/start.S
 @@ -82,8 +81,9 @@ cpu_init_crit:
         orr     r0, r0, #0x00001000     @ set bit 12 (I) I-Cache

         /* Prepare to disable the MMU */
 -       adr     r2, mmu_disable_phys
 -       sub     r2, r2, #(CONFIG_SYS_PHY_UBOOT_BASE - CONFIG_SYS_TEXT_BASE) 
 +       /* Ryan TODO ....*/ 
 +#      adr     r2, mmu_disable_phys 
 +#      sub     r2, r2, #(CONFIG_SYS_PHY_UBOOT_BASE - CONFIG_SYS_TEXT_BASE)
         b       mmu_disable

         .align 5
 @@ -92,7 +92,7 @@ mmu_disable:
         mcr     p15, 0, r0, c1, c0, 0
         nop
         nop
 -       mov     pc, r2 
 +#      mov     pc, r2
  mmu_disable_phys:

  #endif