staging: et131x: Use for loop to initialise contiguous registers to zero

Replace a long list of contiguous writel() calls with a for loop iterating
over the same values.

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

diff --cc drivers/staging/et131x/et131x.c
Simple merge