atf: add patch to fix build without bc(1)

[sideeffect42]

This patch fixes mysterious invalid suffix "x" on integer constant errors on build systems without the bc(1) command installed:

plat/nxp/common/setup/ls_bl2_el3_setup.c: In function ‘ls_bl2_el3_plat_arch_setup’:
<command-line>: error: invalid suffix "x" on integer constant
plat/nxp/common/setup/ls_bl2_el3_setup.c:189:31: note: in expansion of macro ‘BL2_BASE’
  189 |                               BL2_BASE,
      |                               ^~~~~~~~
<command-line>: error: invalid suffix "x" on integer constant
plat/nxp/common/setup/ls_bl2_el3_setup.c:190:63: note: in expansion of macro ‘BL2_BASE’
  190 |                               (unsigned long)(&__BL2_END__) - BL2_BASE,
      |                                                               ^~~~~~~~
make: *** [Makefile:1239: /usr/src/lx2160a_build/build/atf/build/lx2160acex7/release/bl2/ls_bl2_el3_setup.o] Error 1

The potential issues, should addresses grow larger than 2 GiB, remain unchanged, because the usage of bc(1) provided no advantages here as the addresses were always calculated in arithmetic expansions for which POSIX.1-2024 only requires a signed long.