octeontx2-af: serialize bar2 alias access

commit 2511967a709f47854c892757dab02786c27bebcc from
git@git.assembla.com:cavium/WindRiver.linux.git

Adds mutex lock to serialize the bar2 alias access as XXX_AF_BAR2_SEL
can't be used at a time by multiple pci functions.

Signed-off-by: Srujana Challa <schalla@marvell.com>
Change-Id: I7d33566c8cf9129329a3b1508746751820b478ab
Reviewed-on: https://sj1git1.cavium.com/c/IP/SW/kernel/linux/+/87172


Reviewed-by: Nithin Kumar Dabilpuram <ndabilpuram@marvell.com>
Reviewed-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Tested-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Signed-off-by: Ruiqiang Hao <Ruiqiang.Hao@windriver.com>