mb/asus/p2b: Drop select SMP

Variants that select BASE_ASUS_P2B_D will also get
MAX_CPUS==2 below, so this was redundant.

Change-Id: I9048a4821f19d90e1489b09e294d2551941abf10
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43809
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/asus/p2b/Kconfig

@@ -7,7 +7,6 @@ config BASE_ASUS_P2B_D
 	select SDRAMPWR_4DIMM
 	select HAVE_MP_TABLE
 	select IOAPIC
-	select SMP
 
 config BOARD_SPECIFIC_OPTIONS
 	def_bool y