[llvm-nm] Fix docs and help text for --print-size

The --print-size help text and documentation claimed that the size was
printed instead of the address, but this is incorrect. It is printed as
well as the address. This patch fixes this issue.

Reviewed by: MaskRay, mtrent, ruiu

Differential Revision: https://reviews.llvm.org/D63142

llvm-svn: 363136