nvmem: stm32: move STM32MP15_BSEC_NUM_LOWER in config

Support STM32MP15_BSEC_NUM_LOWER in stm32 romem config to prepare
the next SoC in STM32MP family.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20221118063932.6418-2-srinivas.kandagatla@linaro.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>