regulator: dbx500: remove unused functions in dbx500-prcmu.c

We get 2 warnings when building kernel with W=1:
drivers/regulator/dbx500-prcmu.c:78:6: warning: no previous prototype for 'ux500_regulator_suspend_debug' [-Wmissing-prototypes]
drivers/regulator/dbx500-prcmu.c:87:6: warning: no previous prototype for 'ux500_regulator_resume_debug' [-Wmissing-prototypes]

In fact, these functions are unused in
dbx500-prcmu.c, but should be removed.

So this patch removes the unused functions.

Signed-off-by: Baoyou Xie <baoyou.xie@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mark Brown <broonie@kernel.org>