lib/libfdt/: General aesthetic/style fixes.

A number of style fixes across the files in this directory, including:

 * Correct invalid kernel-doc content.
 * Tidy up massive comment in fdt_region.c.
 * Use correct spelling of "U-Boot".
 * Replace tests of "! <var>" with "!<var>".
 * Replace "libfdt_env.h" with <libfdt_env.h>.

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Acked-by: Simon Glass <sjg@chromium.org>

lib/libfdt/Makefile

@@ -5,5 +5,13 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-obj-y += fdt.o fdt_ro.o fdt_rw.o fdt_strerror.o fdt_sw.o fdt_wip.o \
-	fdt_empty_tree.o fdt_addresses.o fdt_region.o
+obj-y += \
+	fdt.o \
+	fdt_ro.o \
+	fdt_rw.o \
+	fdt_strerror.o \
+	fdt_sw.o \
+	fdt_wip.o \
+	fdt_empty_tree.o \
+	fdt_addresses.o \
+	fdt_region.o