net/ncsi: Fix gma flag setting after response

[ Upstream commit 9e860947d8d7a1504476ac49abfce90a4ce600f3 ]

gma_flag was set at the time of GMA command request but it should
only be set after getting successful response. Movinng this flag
setting in GMA response handler.

This flag is used mainly for not repeating GMA command once
received MAC address.

Signed-off-by: Vijay Khemka <vijaykhemka@fb.com>
Reviewed-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: 790071347a0a ("net/ncsi: change from ndo_set_mac_address to dev_set_mac_address")
Signed-off-by: Sasha Levin <sashal@kernel.org>