include soc.h in main.c
include soc.h in main.c

While building with Zephyr 1.12 for the nucleo_f091rc I got undefined
reference to __set_MSP() during linking. Including soc.h fixes the
problem. Thanks carlesc.

Signed-off-by: Evan Gates <178b62e73cc3fab9e30bf27b2372c9ff92401915@gnarbox.com>

ATmobica/mcuboot,tamban01/mcuboot,utzig/mcuboot,runtimeco/mcuboot,runtimeco/mcuboot,ATmobica/mcuboot,runtimeco/mcuboot,runtimeco/mcuboot,utzig/mcuboot,runtimeco/mcuboot,ATmobica/mcuboot,tamban01/mcuboot,tamban01/mcuboot,tamban01/mcuboot,utzig/mcuboot,utzig/mcuboot,ATmobica/mcuboot,ATmobica/mcuboot,utzig/mcuboot,tamban01/mcuboot