test/qtest/aspeed_smc-test: Support to test AST2600

test/qtest/aspeed_smc-test: Support to test AST2600

Add test_ast2600_evb function and reused testcases for AST2600 testing.
The spi base address, flash base address and ce index of fmc_cs0 are
0x1E620000, 0x20000000 and 0, respectively.
The default flash model of fmc_cs0 is "mx66u51235f" whose size is 64MB,
so set jedec_id 0xc2253a.

Signed-off-by: Jamin Lin <jamin_lin@aspeedtech.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/r/20241127091543.1243114-7-jamin_lin@aspeedtech.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>