thermal/drivers/k3_j72xx_bandgap: Simplify k3_thermal_get_temp() function

The k3_thermal_get_temp() function can be simplified to return only
the result of k3_bgp_read_temp() without needing the 'ret' variable

Signed-off-by: Bryan Brattlof <bb@ti.com>
Link: https://lore.kernel.org/r/20221031232702.10339-2-bb@ti.com


Signed-off-by: Daniel Lezcano <daniel.lezcano@kernel.org>