mmc: vub300: fix type of firmware_rom_wait_states module parameter

You didn't mean this to be a bool.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Tony Olech <tony.olech@elandigitalsystems.com>
Cc: <stable@kernel.org>
Signed-off-by: Chris Ball <cjb@laptop.org>