MAINTAINERS: remove obsolete entry after file renaming

MAINTAINERS: remove obsolete entry after file renaming

Commit f16861b12fa0 ("regulator: rename da903x to da903x-regulator") missed
to adjust the DIALOG SEMICONDUCTOR DRIVERS section in MAINTAINERS.

Hence, ./scripts/get_maintainer.pl --self-test=patterns complains:

  warning: no file matches    F:    drivers/regulator/da903x.c

The da903x-regulator.c file is already covered by the pattern
drivers/regulator/da9???-regulator.[ch] in the section.

So, simply remove the non-matching file entry in MAINTAINERS.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Link: https://lore.kernel.org/r/20200628180229.5068-1-lukas.bulwahn@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>