drivers : counter: clean up usage of "USE_STM32_LL"

clean up usage of select USE_STM32_LL_RCC, USE_STM32_LL_EXTI
and USE_STM32_LL_PWR from Kconfig.stm32
this modifications due to the include unconditionally of
stm32xxxx_ll_rcc.h, stm32xxxx_ll_exti.h and
stm32xxxx_ll_pwr.h in the HAL.

Signed-off-by: Khaoula Bidani <khaoula.bidani-ext@st.com>