spi/davinci: fix module build error

Fix below module build error:

  CC [M]  drivers/spi/spi-davinci.o
drivers/spi/spi-davinci.c:774:1: error: '__mod_of_device_table' aliased
to undefined symbol 'davini_spi_of_match'
drivers/spi/spi-davinci.c:774:1: error: '__mod_of_device_table' aliased
to undefined symbol 'davini_spi_of_match'
make[2]: *** [drivers/spi/spi-davinci.o] Error 1
make[1]: *** [drivers/spi] Error 2
make[1]: *** Waiting for unfinished jobs....
make: *** [drivers] Error 2

Signed-off-by: Manjunathappa, Prakash <prakash.pm@ti.com>
Acked-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>