kbuild: move bin2c back to scripts/ from scripts/basic/

kbuild: move bin2c back to scripts/ from scripts/basic/

Commit c98af3530612 ("bin2c: move bin2c in scripts/basic") moved bin2c
to the scripts/basic/ directory, incorrectly stating "Kexec wants to
use bin2c and it wants to use it really early in the build process.
See arch/x86/purgatory/ code in later patches."

Commit 45586306da78 ("Revert "kexec/purgatory: Add clean-up for
purgatory directory"") and commit fc1bf3d8221c ("x86/build: Remove
unnecessary preparation for purgatory") removed the redundant
purgatory build magic entirely.

That means that the move of bin2c was unnecessary in the first place.

fixdep is the only host program that deserves to sit in the
scripts/basic/ directory.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>