staging: mt7621-mmc: Find response of SD_APP_OP_COND by default

The response type of the SD_APP_OP_COND command is correctly
determined using the mmc_resp_type macro, because the only use of that
opcode, mmc_send_app_op_cond, correctly places MMC_RSP_R3 in cmd.flags.

So there is no need to treat that opcode separately.

Signed-off-by: Christian Lütke-Stetzkamp <christian@lkamp.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>