clk: vt8500: fix gcc-4.9 warnings

This fixes some false positive warnings we get with older compiler
versions:

clk-vt8500.c: In function ‘wm8650_find_pll_bits’:
clk-vt8500.c:430:12: ‘best_div2’ may be used uninitialized in this function
clk-vt8500.c:429:12: ‘best_div1’ may be used uninitialized in this function
clk-vt8500.c:428:14: ‘best_mul’ may be used uninitialized in this function
clk-vt8500.c: In function ‘wm8750_find_pll_bits’:
clk-vt8500.c:509:12: ‘best_div2’ may be used uninitialized in this function
clk-vt8500.c:508:12: ‘best_div1’ may be used uninitialized in this function
clk-vt8500.c:507:14: ‘best_mul’ may be used uninitialized in this function
clk-vt8500.c: In function ‘wm8850_find_pll_bits’:
clk-vt8500.c:560:12: ‘best_div2’ may be used uninitialized in this function
clk-vt8500.c:559:12: ‘best_div1’ may be used uninitialized in this function
clk-vt8500.c:558:14: ‘best_mul’ may be used uninitialized in this function

As the local variables are only use for temporaries, we can just
as well assign the final values directly, which also makes the
code slightly shorter.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Roman Volkov <rvolkov@v1ros.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>