clk: sophgo: Avoid -Wsometimes-uninitialized in sg2042_clk_pll_set_rate()

clk: sophgo: Avoid -Wsometimes-uninitialized in sg2042_clk_pll_set_rate()

Clang warns (or errors with CONFIG_WERROR=y):

  drivers/clk/sophgo/clk-sg2042-pll.c:396:6: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
    396 |         if (sg2042_pll_enable(pll, 0)) {
        |             ^~~~~~~~~~~~~~~~~~~~~~~~~
  drivers/clk/sophgo/clk-sg2042-pll.c:418:9: note: uninitialized use occurs here
    418 |         return ret;
        |                ^~~
  drivers/clk/sophgo/clk-sg2042-pll.c:396:2: note: remove the 'if' if its condition is always false
    396 |         if (sg2042_pll_enable(pll, 0)) {
        |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    397 |                 pr_warn("Can't disable pll(%s), status error\n", pll->hw.init->name);
        |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    398 |                 goto out;
        |                 ~~~~~~~~~
    399 |         }
        |         ~
  drivers/clk/sophgo/clk-sg2042-pll.c:393:9: note: initialize the variable 'ret' to silence this warning
    393 |         int ret;
        |                ^
        |                 = 0
  1 error generated.

sg2042_pll_enable() only ever returns zero, so this situation cannot
happen, but clang does not perform interprocedural analysis, so it
cannot know this to avoid the warning. Make it clearer to the compiler
by making sg2042_pll_enable() void and eliminate the error handling in
sg2042_clk_pll_set_rate(), which clears up the warning, as ret will
always be initialized.

Fixes: 48cf7e01386e ("clk: sophgo: Add SG2042 clock driver")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20240710-clk-sg2042-fix-sometimes-uninitialized-pll_set_rate-v1-1-538fa82dd539@kernel.org
Signed-off-by: Stephen Boyd <sboyd@kernel.org>