These drivers can be useful on other MT76xx SoCs, which have compatible
peripherals.  The drivers were selectable in Kconfig, but they were
quietly excluded from the build because the SOC_MT7621 chip was not
selected.  So, make the Makefiles use the same flags as Kconfig for
these drivers.

mt7621-dma and mt7621-dts are left alone because they truly do require
that SoC.

I have personally confirmed that the mt7621-spi driver works on the
MT7688, which was what prompted this change.

Cc: linux-kernel@vger.kernel.org
Cc: devel@driverdev.osuosl.org
Cc: NeilBrown <neil@brown.name>
Cc: sergio.paracuellos@gmail.com
Signed-off-by: George Hilliard <thirtythreeforty@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>