staging: et131x: Only configure regs if link state changes

Some config regs get set whenever adjust_link() is called. Change this
so that these registers only get set when the link state changes to UP.

Also remove unnecessary second assignment of boot_coma.

Signed-off-by: Mark Einon <mark.einon@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>