net: dsa: microchip: fix build warning

In commit 65a93833 ("net: dsa: microchip: fix initial port flush
problem"), the build warning of an unused variable showed up.  Fix this
by removing the variable entirely.

Fixes: 65a93833 ("net: dsa: microchip: fix initial port flush problem")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>