[ARM] remove unused header file: arch/arm/mach-s3c2410/bast.h

Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>