There are mismatch between the prototype declarations and the functions.
Protoype : nrfx_power.h
int nrfx_power_init(nrfx_power_config_t const * p_config);
int nrfx_power_constlat_mode_request(void);
int nrfx_power_constlat_mode_free(void);
Implementation : nrfx_power.c
nrfx_err_t nrfx_power_init(nrfx_power_config_t const * p_config)
nrfx_err_t nrfx_power_constlat_mode_request(void)
nrfx_err_t nrfx_power_constlat_mode_free(void)
There are mismatch between the prototype declarations and the functions.
Protoype : nrfx_power.h
int nrfx_power_init(nrfx_power_config_t const * p_config);int nrfx_power_constlat_mode_request(void);int nrfx_power_constlat_mode_free(void);Implementation : nrfx_power.c
nrfx_err_t nrfx_power_init(nrfx_power_config_t const * p_config)nrfx_err_t nrfx_power_constlat_mode_request(void)nrfx_err_t nrfx_power_constlat_mode_free(void)