efi: libstub: Undeprecate the command line initrd loader

The initrd= command line loader can be useful for development, but it
was limited to loading files from the same file system as the loaded
kernel (and it didn't work on x86 mixed mode).

As both issues have been fixed, and the initrd= can now be used with
files residing on any simple file system exposed by the EFI firmware,
let's permit it to be enabled on RISC-V and LoongArch, which did not
support it up to this point.

Note that LoadFile2 remains the preferred option, as it is much simpler
to use and implement, but generic loaders (including the UEFI shell) may
not implement this so there, initrd= can now be used as well (if enabled
in the build)
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

drivers/firmware/efi/Kconfig

@@ -143,13 +143,16 @@ config EFI_GENERIC_STUB_INITRD_CMDLINE_LOADER
 	bool "Enable the command line initrd loader" if !X86
 	depends on EFI_STUB && (EFI_GENERIC_STUB || X86)
 	default y if X86
-	depends on !RISCV && !LOONGARCH
 	help
 	  Select this config option to add support for the initrd= command
-	  line parameter, allowing an initrd that resides on the same volume
-	  as the kernel image to be loaded into memory.
-
-	  This method is deprecated.
+	  line parameter, allowing an initrd to be loaded into memory that
+	  resides on a file system backed by an implementation of
+	  EFI_SIMPLE_FILE_SYSTEM_PROTOCOL.
+
+	  This method has been superseded by the simpler LoadFile2 based
+	  initrd loading method, but the initrd= loader is retained as it
+	  can be used from the UEFI Shell or other generic loaders that
+	  don't implement the Linux specific LoadFile2 method.
 
 config EFI_BOOTLOADER_CONTROL
 	tristate "EFI Bootloader Control"