ARM: aspeed: Drop unneeded select of HAVE_SMP

Support for the 6th generation Aspeed SoCs depends on ARCH_MULTI_V7.
As the latter selects HAVE_SMP, there is no need for MACH_ASPEED_G6 to
select HAVE_SMP.

Link: https://lore.kernel.org/r/20200505150722.1575-6-geert+renesas@glider.be


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Joel Stanley <joel@jms.id.au>
Cc: Andrew Jeffery <andrew@aj.id.au>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>