kernel/elf: Ignore PT_EH_FRAME for kernel add-ons.

We do the same thing in runtime_loader. Silences a lot
of warnings.

src/system/kernel/elf.cpp

@@ -2288,6 +2288,9 @@ load_kernel_add_on(const char *path)
 			case PT_STACK:
 				// we don't use it
 				continue;
+			case PT_EH_FRAME:
+				// not implemented yet, but can be ignored
+				continue;
 			default:
 				dprintf("%s: unhandled pheader type %#" B_PRIx32 "\n", fileName,
 					programHeaders[i].p_type);