staging: nvec: Fix typo s/I2C_SL_NEWL/I2C_SL_NEWSL/

The constant I2C_SL_NEWL meant "new slave", but the
S was missing.

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