hw/arm/aspeed: fix AST2500/AST2600 EVB fmc model

hw/arm/aspeed: fix AST2500/AST2600 EVB fmc model

Current fmc model of AST2500 EVB and AST2600 EVB can't emulate quad
mode properly so fix them using equivalent mx25l25635e and mx66u51235f
respectively.

These default settings still can be overridden using the 'fmc-model'
command line option.

Reported-by: Graeme Gregory <quic_ggregory@quicinc.com>
Signed-off-by: Jae Hyun Yoo <quic_jaehyoo@quicinc.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20220402184427.4010304-1-quic_jaehyoo@quicinc.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>