ARM: S3C24XX: remove unused header <mach/bast-pmu.h>

Since (at least) v2.6.12-rc2 there has been a bast-pmu.h header in the
tree. Currently it can be found at
arch/arm/mach-s3c24xx/include/mach/bast-pmu.h.

It seems that during that entire period nothing included that header and
that none of the named constants it provided were ever used. That header
can safely be removed.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>