ARM: davinci: clock: return 0 upon error from clk_round_rate()

ARM: davinci: clock: return 0 upon error from clk_round_rate()

clk_round_rate() should return 0 now upon an error, rather than returning
a negative error code.  This is because clk_round_rate() is being changed
to return an unsigned return type rather than a signed type, since some
clock sources can generate rates higher than (2^31)-1 Hz.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Philip Avinash <avinashphilip@ti.com>
Cc: Sekhar Nori <nsekhar@ti.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>