wifi: brcmsmac: phy_lcn: Remove dead code in wlc_lcnphy_radio_2064_channel_tune_4313()

The variable rfpll_doubler is initialized to 0 and then unconditionally
set to 1 on the very next line, making the subsequent check for
!rfpll_doubler always evaluate to false. This results in logically
dead code that has never been executed.

Remove the unused variable, the unreachable conditional branch, and
simplify the fpfd calculation to directly use the PLL doubler values.

Signed-off-by: Chelsy Ratnawat <chelsyratnawat2001@gmail.com>
Acked-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Link: https://patch.msgid.link/20260403193324.141753-1-chelsyratnawat2001@gmail.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>