regulator: wm8350: Remove unused variable

Commit 8f45acb5 ("regulator: wm8350: Pass NULL data with REGULATION_OUT
and UNDER_VOLTAGE events") introduced the following build warning:

drivers/regulator/wm8350-regulator.c: In function 'pmic_uv_handler':
drivers/regulator/wm8350-regulator.c:1154:17: warning: unused variable 'wm8350' [-Wunused-variable]

Remove 'wm8350' as it is unused now.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>