staging: nvec: ps2: Always sample 4 bytes instead of just 1

Get 4 bytes of data from nvec at once instead of just a single
byte. This makes the driver more similar to nvidias and might
improve reliability.

Signed-off-by: Julian Andres Klode <jak@jak-linux.org>
Acked-by: Marc Dietrich <marvin24@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>