efi_loader: fix Sphinx warning

Brackets '[' need to be escaped to avoid a build warning

    lib/efi_loader/efi_image_loader.c:223:
    WARNING: Inline strong start-string without end-string.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
40 jobs for efi-2021-07 in 70 minutes and 32 seconds (queued for 8 minutes and 54 seconds)
Status Name Job ID Coverage
  Testsuites
passed Build envtools #276772

00:00:13

passed Build tools-only #276771

00:00:13

passed Check for configs without MAINTAINERS entry #276770

00:00:10

passed cppcheck #276766

00:00:32

passed grep TODO/FIXME/HACK #276767

00:00:12

passed htmldocs #276768

00:00:52

passed Run binman, buildman, dtoc, Kconfig and patman testsuites #276773

00:01:03

passed Run tests for Nokia RX-51 (aka N900) #276774

00:03:06

passed sloccount #276769

00:00:37

 
  Test.Py
passed evb-ast2500 test.py #276779

00:01:01

passed integratorcp_cm926ejs test.py #276781

00:00:57

passed qemu_arm64 test.py #276783

00:03:19

passed qemu_arm test.py #276782

00:01:19

passed qemu_malta64el test.py #276787

00:00:38

passed qemu_malta64 test.py #276786

00:00:37

passed qemu_maltael test.py #276785

00:00:59

passed qemu_malta test.py #276784

00:00:58

passed qemu-ppce500 test.py #276788

00:00:42

passed qemu-riscv32_spl test.py #276791

00:01:06

passed qemu-riscv32 test.py #276789

00:01:18

passed qemu-riscv64_spl test.py #276792

00:01:08

passed qemu-riscv64 test.py #276790

00:01:02

passed qemu-x86_64 test.py #276794

00:01:36

passed qemu-x86 test.py #276793

00:01:20

passed r2dplus_i82557c test.py #276795

00:00:58

passed r2dplus_pcnet test.py #276796

00:00:37

passed r2dplus_rtl8139 test.py #276797

00:00:57

passed r2dplus_tulip test.py #276798

00:00:36

passed sandbox_flattree test.py #276780

00:00:56

passed sandbox_noinst_test.py #276778

00:00:57

passed sandbox_spl test.py #276777

00:01:31

passed sandbox test.py #276775

00:03:55

passed sandbox with clang test.py #276776

00:04:52

passed xilinx_versal_virt test.py #276800

00:00:40

passed xilinx_zynq_virt test.py #276799

00:01:02

passed xtfpga test.py #276801

00:00:56

 
  World Build
passed build all 32bit ARM platforms #276802

00:48:37

passed build all 64bit ARM platforms #276803

00:17:10

passed build all other platforms #276805

00:05:25

passed build all PowerPC platforms #276804

00:05:52