MAINTAINERS: add Rust FW abstractions to FIRMWARE LOADER

Add missing file path of the Rust abstractions to the maintainers entry,
until we can move it to 'drivers/base/firmware_loader/'.

CC: Luis Chamberlain <[email protected]>
CC: Russ Weight <[email protected]>
CC: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Danilo Krummrich <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: dakr

MAINTAINERS

@@ -8573,6 +8573,7 @@ L:	[email protected]
 S:	Maintained
 F:	Documentation/firmware_class/
 F:	drivers/base/firmware_loader/
+F:	rust/kernel/firmware.rs
 F:	include/linux/firmware.h
 
 FLEXTIMER FTM-QUADDEC DRIVER