arm: socfpga: Fix SR1500 env position

Move the inclusion of the common socfpga configuration file further
down in the sr1500 configuration, so that the socfpga_common.h can
check if environment is in SPI NOR and it's location is defined and
if it is not, define default location.

This fixes "arm: socfpga: Enabling U-Boot environment support in QSPI"
which introduced a minor warning.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Chin Liang See <clsee@altera.com>
Cc: Dinh Nguyen <dinguyen@opensource.altera.com>
Cc: Dinh Nguyen <dinh.linux@gmail.com>
Cc: Pavel Machek <pavel@denx.de>
Cc: Marek Vasut <marex@denx.de>
Cc: Stefan Roese <sr@denx.de>