tools/power turbostat: Fix undefined behavior in pmt_gen_value_mask()

The function uses plain int literal '1' for bit shifting, which causes
undefined behavior when msb >= 31. This is because shifting a 32-bit int
by 32 or more bits is undefined behavior in C. Fix by using 1ULL
(unsigned long long) instead of 1 to ensure 64-bit arithmetic on all
platforms.

Signed-off-by: Kaushlendra Kumar <kaushlendra.kumar@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>