DEVELOPERS: add Christophe Priouzeau as contact for STM32 defconfigs

DEVELOPERS: add Christophe Priouzeau as contact for STM32 defconfigs

Christophe has recently taken care of those defconfigs, so let's add
him as a contact for those defconfigs, so that he receives build
failure notifications and is Cc'ed on patches.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: Christophe PRIOUZEAU <christophe.priouzeau@st.com>
Cc: Lee Jones <lee.jones@linaro.org>
Acked-by: Christophe Priouzeau <christophe.priouzeau@st.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>