Do not touch PLL_BYPASS bit as a part of clk_pll3_enable/disable
execution. For a number of platforms (e.g. Vybrid, i.MX6SL) PLL_BYPASS
is specified as a bit controlling a clock MUX represented by a
dedicated 'struct clk'. Altering that bit as a part of
clk_pll3_enable/disable is equivalent to calling clk_set_parent() and
it makes in the following code:

clk_enable(clk_disable(<some pll>))

change clock chain instead of being a no-op.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>