Factor out the common code in the accumulation functions for core and
socket accumulation.

While at it, handle the return value of the amd_create_sensor() function.
Signed-off-by: Naveen Krishna Chatradhi <nchatrad@amd.com>
Link: https://lore.kernel.org/r/20200929105322.8919-4-nchatrad@amd.comSigned-off-by: Guenter Roeck <linux@roeck-us.net>