Add memory barrier after pll setting
Add memory barrier after pll setting

From testing, found add memory barrier after pll setting the ddr
setting will be much stable. So add this as a temporary fixing.

Signed-off-by: Leo Yan <a38ad1fbd0b3373e0c012f4d28e16dbce652d487@linaro.org>

jforissier/arm-trusted-firmware,96boards/arm-trusted-firmware,vchong/arm-trusted-firmware,jforissier/arm-trusted-firmware,96boards/arm-trusted-firmware,vchong/arm-trusted-firmware