nhk8815: fix build errors

Fix:
common/libcommon.o: In function `cread_line':
/home/ag/git/u-boot/common/main.c:695: undefined reference to `get_ticks'
/home/ag/git/u-boot/common/main.c:695: undefined reference to `get_tbclk'
/home/ag/git/u-boot/common/main.c:698: undefined reference to `get_ticks'

Signed-off-by: Anatolij Gustschin <agust@denx.de>
Cc: Alessandro Rubini <rubini@unipv.it>
Acked-by: Marek Vasut <marex@denx.de>
Acked-by: Alessandro Rubini <rubini@unipv.it>