mfd: tps65912-spi: Add missing of table registration

MODULE_DEVICE_TABLE(of, <of_match_table> should be called to complete DT
OF mathing mechanism and register it.

Before this patch:
modinfo drivers/mfd/tps65912-spi.ko | grep alias
alias:          spi:tps65912

After this patch:
modinfo drivers/mfd/tps65912-spi.ko | grep alias
alias:          of:N*T*Cti,tps65912C*
alias:          of:N*T*Cti,tps65912
alias:          spi:tps65912

Reported-by: Javier Martinez Canillas <javier@dowhile0.org>
Signed-off-by: Daniel Gomez <dagmcr@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/tps65912-spi.c

@@ -27,6 +27,7 @@ static const struct of_device_id tps65912_spi_of_match_table[] = {
 	{ .compatible = "ti,tps65912", },
 	{ /* sentinel */ }
 };
+MODULE_DEVICE_TABLE(of, tps65912_spi_of_match_table);
 
 static int tps65912_spi_probe(struct spi_device *spi)
 {