efi_loader: initialize the RNG protocol after the TCC2

Due to U-Boot's lazy binding the RNG presented by the TCG is not available
until the EFI_TCG2 protocol has been initialized.  Since the TPM has a
built-in RNG device we can use for the OS randomization, move the RNG
protocol installation after the TCG.

Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>