ARC: set boot print log level to PR_INFO

Some of the boot printing code had printk() w/o explicit log level.

This patch introduces consistency allowing platforms to switch to less
verbose console logging using cmdline.

NPS400 with 4K CPUs needs to avoid the cpu info printing for faster
bootup.

Signed-off-by: Noam Camus <noamca@mellanox.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>