rust: Use grep -Ev rather than relying on GNU grep

While GNU grep supports '\|' when in basic regular expression mode, not
all grep implementations do (notably toybox grep, used to build the
Android kernel, does not). Switching to grep -Ev enables extended
regular expressions which includes support for the '|' operator.

Signed-off-by: Matthew Maurer <mmaurer@google.com>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Tested-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20230928201421.2296518-1-mmaurer@google.com
[ Reworded for typo. ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

rust/Makefile

@@ -336,13 +336,13 @@ quiet_cmd_bindgen = BINDGEN $@
 		$(bindgen_target_cflags) $(bindgen_target_extra)
 
 $(obj)/bindings/bindings_generated.rs: private bindgen_target_flags = \
-    $(shell grep -v '^#\|^$$' $(srctree)/$(src)/bindgen_parameters)
+    $(shell grep -Ev '^#|^$$' $(srctree)/$(src)/bindgen_parameters)
 $(obj)/bindings/bindings_generated.rs: $(src)/bindings/bindings_helper.h \
     $(src)/bindgen_parameters FORCE
 	$(call if_changed_dep,bindgen)
 
 $(obj)/uapi/uapi_generated.rs: private bindgen_target_flags = \
-    $(shell grep -v '^#\|^$$' $(srctree)/$(src)/bindgen_parameters)
+    $(shell grep -Ev '^#|^$$' $(srctree)/$(src)/bindgen_parameters)
 $(obj)/uapi/uapi_generated.rs: $(src)/uapi/uapi_helper.h \
     $(src)/bindgen_parameters FORCE
 	$(call if_changed_dep,bindgen)