wifi: rtlwifi: Remove unused rtl_usb_{resume|suspend}

wifi: rtlwifi: Remove unused rtl_usb_{resume|suspend}

rtl_usb_resume() and rtl_usb_suspend() are trivial stubs that were
added in 2011's
commit 2ca20f79e0d8 ("rtlwifi: Add usb driver")
but aren't wired up anywhere (though commit 442888c706e9 ("rtlwifi:
rtl8192cu: Add routines dm, fw, led and sw")  added commented
out assignments).

Remove them.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20250425235340.288340-2-linux@treblig.org