firmware: arm_scmi: use strlcpy to ensure NULL-terminated strings

Replace all the memcpy() for copying name strings from the firmware with
strlcpy() to make sure we are bounded by the source buffer size and we
also always have NULL-terminated strings.

This is needed to avoid out of bounds accesses if the firmware returns
a non-terminated string.

Reported-by: Olof Johansson <olof@lixom.net>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>