x86/hwmon: (coretemp) cosmetic cleanup

"break" after "return" is at best bogus (good compilers even warn about
the "break" being unreachable).

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Cc: Rudolf Marek <r.marek@assembler.cz>
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>