ANDROID: devlink: Select NET_DEVLINK in Kconfig.gki

Devlink region can provide a channel to catch modem boot log and save it
to user space through driver, but it can't be setted by just add
CONFIG_NET_DEVLINK=y in gki_defconfig, so we choose to select Net_DEVLINK
in Kconfig.gki to enable CONFIG_NET_DEVLINK by your advice.

Bug: 283707518
Change-Id: Id1e1be3797e6c8e4f737def999054cac3b96afa7
Signed-off-by: Po-Wen Kao <powen.kao@mediatek.com>
Signed-off-by: Michael Cai <michael.cai@mediatek.com>