net: phy: micrel: Make the GPIO to be non-exclusive

The same GPIO line can be shared by multiple phys for the coma mode pin.
If that is the case then, all the other phys that share the same line
will failed to be probed because the access to the gpio line is not
non-exclusive.
Fix this by making access to the gpio line to be nonexclusive using flag
GPIOD_FLAGS_BIT_NONEXCLUSIVE. This allows all the other PHYs to be
probed.

Fixes: 738871b0

 ("net: phy: micrel: add coma mode GPIO")
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Link: https://lore.kernel.org/r/20220830064055.2340403-1-horatiu.vultur@microchip.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>