libc: remove no longer valid kconfig comment

After commit 9a0aebc5fd9c39fb3d4a4a9741fcff7e1695e807,
the exclusion of qemu_x86_tiny is no longer and the "depends on"
option was removed. However, the comment about that remained.
Remove the comment as it is no longer valid.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>
1 file changed