regulator: Fix a typo in da903x.c

regulator: Fix a typo in da903x.c

Fix below build errors which is introduced by commit c172708
"regulator: core: Use a struct to pass in regulator runtime configuration".

  CC      drivers/regulator/da903x.o
drivers/regulator/da903x.c: In function 'da903x_regulator_probe':
drivers/regulator/da903x.c:541: error: 'conifg' undeclared (first use in this function)
drivers/regulator/da903x.c:541: error: (Each undeclared identifier is reported only once
drivers/regulator/da903x.c:541: error: for each function it appears in.)
make[2]: *** [drivers/regulator/da903x.o] Error 1
make[1]: *** [drivers/regulator] Error 2
make: *** [drivers] Error 2

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>