[kmac,prim_sha2/rtl] Remove unused conv_endian64 function

Removing this code now so it won't have to be fixed in the subsequent
commit.

Signed-off-by: Andreas Kurth <adk@lowrisc.org>

hw/ip/kmac/rtl/kmac_pkg.sv

@@ -421,9 +421,4 @@ package kmac_pkg;
     conv_endian32 = (swap) ? conv_data : v ;
   endfunction : conv_endian32
 
-  function automatic logic [63:0] conv_endian64( input logic [63:0] v, input logic swap);
-    logic [63:0] conv_data = {<<8{v}};
-    conv_endian64 = (swap) ? conv_data : v ;
-  endfunction : conv_endian64
-
 endpackage : kmac_pkg

hw/ip/prim/rtl/prim_sha2_pkg.sv

@@ -117,11 +117,6 @@ package prim_sha2_pkg;
     conv_endian32 = (swap) ? conv_data : v;
   endfunction : conv_endian32
 
-  function automatic sha_word64_t conv_endian64(input sha_word64_t v, input logic swap);
-    sha_word64_t conv_data = {<<8{v}};
-    conv_endian64 = (swap) ? conv_data : v;
-  endfunction : conv_endian64
-
   function automatic sha_word32_t rotr32(input sha_word32_t v, input integer amt);
     rotr32 = (v >> amt) | (v << (32-amt));
   endfunction : rotr32