regulator: core: Avoid device name duplication in NORMAL_GET

regulator: core: Avoid device name duplication in NORMAL_GET

With current code:
	st-gyro-i2c i2c-PRP0001:00: i2c-PRP0001:00 supply vdd not found, using dummy regulator

which looks a bit oververbose.

Replace this with simplified format string for the above case, and drop
"deviceless" case since for all dev_*() macros used in _regulator_get()
the "(null)" will be printed anyway.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200312183245.1612-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>