staging: rts5208: Remove function soft_reset_sd_card()

Remove function soft_reset_sd_card, as all it does is call reset_sd.
Modify call sites of the former to call the latter instead.
Issue found with Coccinelle.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>