firmware: octeontx2: sysfs interface for led blink rate

commit 88bdead7fc0d0b694a25aa5a96051175f99c1188 from
git@git.assembla.com:cavium/WindRiver.linux.git

Added sysfs interface to control the network activity blink rate for
LEDs that are directly connected to Octeon GPIOs

Signed-off-by: Scott Rowberry <rowberry@marvell.com>
Change-Id: I3ca55ca8db6e0aec27f735e68d8cbbb175ee192d
Reviewed-on: https://sj1git1.cavium.com/c/IP/SW/kernel/linux/+/120248
Reviewed-by: Chandrakala Chavva <cchavva@marvell.com>
Tested-by: sa_ip-sw-jenkins <sa_ip-sw-jenkins@marvell.com>
Signed-off-by: Ruiqiang Hao <Ruiqiang.Hao@windriver.com>