[power supply]:missing definition without config

From: fuyao
Date: Fri Nov 15 2019 - 01:07:16 EST


linux-pm:
hi, walk around the power_supply.h file.
call power_supply_get_by_name without the CONFIG_POWER_SUPPLY, cause
error.
if we should use:

#ifdef CONFIG_POWER_SUPPLY
extern extern struct power_supply *power_supply_get_by_name(const char *name);
#else
static inline struct power_supply *
power_supply_get_by_name(const char *name)
{return NULL;}
#endif