soc/integration/builder: remove error when compile_software=False and integrated ROM: when using compile_software=False user knows what he's doing.

litex/soc/integration/builder.py

@@ -127,7 +127,6 @@ class Builder:
     def _initialize_rom(self):
         bios_file = os.path.join(self.output_dir, "software", "bios",
                                  "bios.bin")
-        if self.soc.integrated_rom_size:
         with open(bios_file, "rb") as boot_file:
             boot_data = []
             while True:
@@ -142,14 +141,11 @@ class Builder:
 
         os.makedirs(self.output_dir, exist_ok=True)
 
-        if self.soc.cpu_type is not None and self.compile_software:
-            if self.soc.integrated_rom_size:
-                raise ValueError("Software must be compiled in order to "
-                                 "intitialize integrated ROM")
-
+        if self.soc.cpu_type is not None:
             self._prepare_software()
             self._generate_includes()
             self._generate_software()
+            if self.soc.integrated_rom_size and self.compile_software:
             	self._initialize_rom()
 
         if self.csr_csv is not None: