[util] Allow for CALL NEAR in the option ROM initialisation entry point

Option::ROM currently understands only JMP NEAR and JMP SHORT
instructions in the initialisation entry point.  At least one Broadcom
option ROM has been observed to use a CALL NEAR instruction.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/util/Option/ROM.pm

@@ -180,6 +180,7 @@ our %EXPORT_TAGS = ( all => [ @EXPORT_OK ] );
 
 use constant JMP_SHORT => 0xeb;
 use constant JMP_NEAR => 0xe9;
+use constant CALL_NEAR => 0xe8;
 
 sub pack_init {
   my $dest = shift;
@@ -203,6 +204,9 @@ sub unpack_init {
   } elsif ( $jump == JMP_NEAR ) {
     my $offset = unpack ( "xS", $instr );
     return ( $offset + 6 );
+  } elsif ( $jump == CALL_NEAR ) {
+    my $offset = unpack ( "xS", $instr );
+    return ( $offset + 6 );
   } elsif ( $jump == 0 ) {
     return 0;
   } else {