staging: rtl8188eu: core: Remove function enable_rate_adaptive()

Remove function enable_rate_adaptive as it does nothing except call
Update_RA_Entry.
Modify call site of enable_rate_adaptive to call Update_RA_Entry
instead.
Issue found with Coccinelle.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Link: https://lore.kernel.org/r/20190712071746.2474-2-nishkadg.linux@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>