ARM: dts: aspeed: ast2600-evb: Enable Quad SPI RX tranfers

ARM: dts: aspeed: ast2600-evb: Enable Quad SPI RX tranfers

Now that the pinctrl definitions of the ast2600 SoC have been fixed,
see commit 925fbe1f7eb6 ("dt-bindings: pinctrl: aspeed-g6: add FWQSPI
function/group"), it is safe to activate QSPI on the ast2600 evb.

Cc: Chin-Ting Kuo <chin-ting_kuo@aspeedtech.com>
Tested-by: Jae Hyun Yoo <quic_jaehyoo@quicinc.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Link: https://lore.kernel.org/r/20220603073705.1624351-1-clg@kaod.org
Signed-off-by: Joel Stanley <joel@jms.id.au>