score: remove unused CPU_SCORE7 Kconfig parameter

This removes the CPU_SCORE7 Kconfig parameter, which is no longer used
anywhere in the source code and Makefiles.

Signed-off-by: Michael Opdenacker <michael.opdenacker@free-electrons.com>
Cc: Chen Liqin <liqin.linux@gmail.com>
Cc: Lennox Wu <lennox.wu@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>