common-pc: enforce 32 bit

ARCH=x86 defaults to 64 bit on modern kernels. So we need to
explicitly disable 64bit in common-pc if we want a 32bit build
(common-pc builds with ARCH=x86, not ARCH=i386)

Signed-off-by: Bruce Ashfield <bruce.ashfield@windriver.com>

bsp/common-pc/common-pc-cpu.cfg

@@ -15,3 +15,4 @@ CONFIG_X86_GENERIC=y
 CONFIG_X86_TSC=y
 CONFIG_X86_MCE=y
 CONFIG_PM=y
+# CONFIG_64BIT is not set