ARM: 8374/1: no longer expose CPU_ARM7TDMI/CPU_ARM9TDMI

Atmel at91x40 is gone, so we no longer have any platform using
either of these two, and we get randconfig failures on NOMMU
kernels if they accidentally get enabled on something that conflicts
with ARMv4T.

This stops short of removing the entire CPU support for now,
but as nothing selects these, it is basically dead code.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>