efi/printf: remove unneeded semicolon

Fix the warning below.
efi/libstub/vsprintf.c:135:2-3: Unneeded semicolon

Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Acked-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/1599633872-36784-1-git-send-email-tiantao6@hisilicon.com
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>