x86: crownbay: Disable boot stage support

x86: crownbay: Disable boot stage support

It is observed that when enabling boot stage support, occasionally
the board reboots during boot over and over again, and eventually
boots to shell. This was seen on my board, but not on Jian's board.
Debugging shows that the TSC timer calibration against PIT fails
as boot stage APIs utilize timer in a very early stage and at that
time TSC/PIT may not be stable enough for the calibration to pass.

Disable it for now.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Cc: Jian Luo <Jian.Luo4@boschrexroth.de>
Reviewed-by: Simon Glass <sjg@chromium.org>