efi_loader: use EFI_EXIT in efi_riscv_get_boot_hartid

After calling EFI_ENTRY we have to call EFI_EXIT before returning.

Add a missing EFI_EXIT().

Fixes: 1ccf87165e38 ("efi_loader: Enable RISCV_EFI_BOOT_PROTOCOL support")
Reported-by: Dave Jones <dave.jones@canonical.com>
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Sunil V L <sunilvl@ventanamicro.com>
diff --git a/lib/efi_loader/efi_riscv.c b/lib/efi_loader/efi_riscv.c
index bccfefd..0641727 100644
--- a/lib/efi_loader/efi_riscv.c
+++ b/lib/efi_loader/efi_riscv.c
@@ -31,7 +31,7 @@
 	EFI_ENTRY("%p, %p",  this, boot_hartid);
 
 	if (this != &riscv_efi_boot_prot || !boot_hartid)
-		return EFI_INVALID_PARAMETER;
+		return EFI_EXIT(EFI_INVALID_PARAMETER);
 
 	*boot_hartid = gd->arch.boot_hart;