dtc/powerpc: remove obsolete .gitignore entries

dtc was moved and .gitignores have been added to the new location. So, we can
delete the old, forgotten ones.
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

arch/powerpc/boot/.gitignore

 addnote
-dtc
 empty.c
 hack-coff
 infblock.c

arch/powerpc/boot/dtc-src/.gitignore

-dtc-lexer.lex.c
-dtc-parser.tab.c
-dtc-parser.tab.h