clk: imx: Fix an out-of-bounds access in dispmix_csr_clk_dev_data

clk: imx: Fix an out-of-bounds access in dispmix_csr_clk_dev_data

When num_parents is 4, __clk_register() occurs an out-of-bounds
when accessing parent_names member. Use ARRAY_SIZE() instead of
hardcode number here.

 BUG: KASAN: global-out-of-bounds in __clk_register+0x1844/0x20d8
 Read of size 8 at addr ffff800086988e78 by task kworker/u24:3/59
  Hardware name: NXP i.MX95 19X19 board (DT)
  Workqueue: events_unbound deferred_probe_work_func
  Call trace:
    dump_backtrace+0x94/0xec
    show_stack+0x18/0x24
    dump_stack_lvl+0x8c/0xcc
    print_report+0x398/0x5fc
    kasan_report+0xd4/0x114
    __asan_report_load8_noabort+0x20/0x2c
    __clk_register+0x1844/0x20d8
    clk_hw_register+0x44/0x110
    __clk_hw_register_mux+0x284/0x3a8
    imx95_bc_probe+0x4f4/0xa70

Fixes: 5224b189462f ("clk: imx: add i.MX95 BLK CTL clk driver")
Cc: stable@vger.kernel.org
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Xiaolei Wang <xiaolei.wang@windriver.com>
Link: https://lore.kernel.org/r/20250619062108.2016511-1-xiaolei.wang@windriver.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>