arm: mvebu: turris_omnia: Fix setting switch CONFIG pins on new board design

It seems that waiting only 10 ms after releasing LAN switch from reset
is not enough for the strapping pins to latch the requested values.
P6_MODE[0] is latched to 0 instead of 1.

Increasing the delay to 50 ms fixes this issue.

Signed-off-by: Marek Behún <kabel@kernel.org>
Reviewed-by: Stefan Roese <sr@denx.de>