All Samsung platforms are now using the Common Clock Framework and the
legacy clock code is being removed, so remove related dead code from
samsung-serial driver as well.
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>