Sparc: Remove fishy VK_WPLT30 special case
I think 9fc29098dfa684de53dd180aa93e94c39c388631 (2014) was misguided
and added the unneeded special case. It probably wanted to handle
R_SPARC_WPLT30/R_SPARC_WDISP30 in PDC/PIC but it's not correct
to check the property in AsmParser.
