parisc: rename "CONFIG_PA7100" to "CONFIG_PA7000"

There's a Makefile line setting cflags for CONFIG_PA7100. But that
Kconfig macro doesn't exist. There is a Kconfig symbol PA7000, which
covers both PA7000 and PA7100 processors. So let's use the corresponding
Kconfig macro.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Helge Deller <deller@gmx.de>