drivers: adc: stm32 adc disable causing endless loop

Setting Oversampling also applies on stm32L5 but disabling
the ADC will cause endless loop except for the stm32L0 serie.
Errata applies only on stm32G0 soc series when
writing ADC_CFGR1 register.

Signed-off-by: Francois Ramu <francois.ramu@st.com>