am335x, guardian: software update available status is stored in AM3352 RTC scracth register

RTC second scratch register[32-bit]:
-zero byte hold boot count value
-first byte hold update available state
-second byte hold version
-third byte hold magic number

Signed-off-by: Gireesh Hiremath <Gireesh.Hiremath@in.bosch.com>

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Link: https://lore.kernel.org/r/20210611161350.2141-17-Gireesh.Hiremath@in.bosch.com
Gbp-Pq: Topic apertis/guardian
Gbp-Pq: Name am335x-guardian-software-update-available-status-is-store.patch