Removing unneeded trailing zero from sdf max units expression

[nvmkuruc]

Description of Change(s)

#2590 replaced some preprocessor expressions with a constexpr use of std::max to compute the maximum number of units. std::max takes an initializer list populated by a macro that appends a , after each element.

The original implementation added 0 to follow the last ,. However, as std::initializer_lists are allowed to have trailing commas, this was unneeded.

Fixes Issue(s)

• I have verified that all unit tests pass with the proposed changes

• I have submitted a signed Contributor License Agreement

[jesschimein]

Filed as internal issue #USD-8953