wifi: rtw89: 8852bt: rfk: use predefined string choice for DPK enable/disable

wifi: rtw89: 8852bt: rfk: use predefined string choice for DPK enable/disable

clang warns precedence of '?:' and '&'. Even though original logic is
correct, use str_enable_disable() to avoid clang confusing. Another way to
fix is to add parentheses around '&', but I choose former one.

  >> drivers/net/wireless/realtek/rtw89/rtw8852bt_rfk.c:1827:46: warning:
     operator '?:' has lower precedence than '&'; '&' will be evaluated
     first [-Wbitwise-conditional-parentheses]
    1827 |                     kidx, dpk->is_dpk_enable & off_reverse ? "enable" : "disable");
         |                           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202407200741.dMG9uvHU-lkp@intel.com/
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20240720021340.12102-3-pkshih@realtek.com