tools/power/x86/intel-speed-select: Enhance get_tdp_info

mbox_get_uncore_p0_p1_info/get_p1_info/get_uncore_mem_freq can be done
inside get_tdp_info().

Fold the code into get_tdp_info().

No functional changes are expected.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
[srinivas.pandruvada@linux.intel.com: changelog edits]
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>