Blackfin: replace "bfin_reset_or_hang()" with "panic()"

The bfin_reset_or_hang function unnecessarily duplicates the panic()
logic based on CONFIG_PANIC_HANG.

This patch deletes 20 lines of code and just calls panic() instead.
This also makes the following generic-restart conversion patch simpler.

Signed-off-by: Kyle Moffett <Kyle.D.Moffett@boeing.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>