[ARM] OMAP: Make dpll4_m4_ck programmable with clk_set_rate()

Filling the set_rate and round_rate fields of dpll4_m4_ck makes
this clock programmable through clk_set_rate().  This is needed
to give omapfb control over the dss1_alwon_fck rate.

This patch includes a fix from Tomi Valkeinen <tomi.valkeinen@nokia.com>.

linux-omap source commits are e42218d45afbc3e654e289e021e6b80c657b16c2 and
9d211b761b3cdf7736602ecf7e68f8a298c13278.

Signed-off-by: Måns Rullgård <mans@mansr.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@nokia.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>