ARM: S5PV210: Fix early uart output in fifo mode

Enabling UART FIFO in bootloader caused the kernel infinite
loop on S5PV210 due to uninitialized fifo_max and fifo_mask global
variables. This patch adds the correct initialization.

Signed-off-by: Alexey Galakhov <agalakhov@gmail.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>