x86: braswell: Fix unexpected crash during Linux kernel boot

x86: braswell: Fix unexpected crash during Linux kernel boot

It was observed that when booting Linux kernel on Intel Cherry Hill
board, unexpected crash happens quite randomly. Sometimes kernel
just oops, while sometimes kernel throws MCE errors and hangs:

  mce: [Hardware Error]: Machine check events logged
  mce: [Hardware Error]: CPU 0: Machine Check: 0 Bank 4: c400000000010151
  mce: [Hardware Error]: TSC 0 ADDR 130f3f2c0
  mce: [Hardware Error]: PROCESSOR 0:406c3 TIME 1508160686 SOCKET 0 APIC 0 microcode 363

This looks like a hardware error per mcelog. After debugging, it
seems turning off turbo mode on the processor does not expose this
behavior, although U-Boot runs OK with turbo mode on. Suspect it is
related to an errata of Braswell processor.

To fix this, remove the Braswell cpu driver which does the turbo
mode configuration, and switch to use the generic cpu-x86 driver.
Also there is a configuration option in the FSP that turns on the
turbo mode and that has been turned off too.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>