Fixup redundant redeclaration of 'csp_rtable_load'

[nickoe]

Would otherwise get:

../../lib/libcsp/include/csp/csp_rtable.h:108:5: warning: redundant redeclaration of 'csp_rtable_load' [-Wredundant-decls]
  108 | int csp_rtable_load(const char * rtable);
      |     ^~~~~~~~~~~~~~~
../../lib/libcsp/include/csp/csp_rtable.h:97:5: note: previous declaration of 'csp_rtable_load' was here
   97 | int csp_rtable_load(const char * rtable);
      |