clk: asm9260: fix __clk_hw_register_fixed_rate_with_accuracy typo

The __clk_hw_register_fixed_rate_with_accuracy() function (with two '_')
does not exist, and apparently never did:

drivers/clk/clk-asm9260.c: In function 'asm9260_acc_init':
drivers/clk/clk-asm9260.c:279:7: error: implicit declaration of function '__clk_hw_register_fixed_rate_with_accuracy'; did you mean 'clk_hw_register_fixed_rate_with_accuracy'? [-Werror=implicit-function-declaration]
  279 |  hw = __clk_hw_register_fixed_rate_with_accuracy(NULL, NULL, pll_clk,
      |       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |       clk_hw_register_fixed_rate_with_accuracy
drivers/clk/clk-asm9260.c:279:5: error: assignment to 'struct clk_hw *' from 'int' makes pointer from integer without a cast [-Werror=int-conversion]
  279 |  hw = __clk_hw_register_fixed_rate_with_accuracy(NULL, NULL, pll_clk,
      |     ^

From what I can tell, __clk_hw_register_fixed_rate() is the correct
API here, so use that instead.

Fixes: 728e3096

 ("clk: asm9260: Use parent accuracy in fixed rate clk")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lkml.kernel.org/r/20200408155402.2138446-1-arnd@arndb.de
Signed-off-by: Stephen Boyd <sboyd@kernel.org>