[ppc4xx] Change board/amcc/acadia/cpr.c to pll.c

Signed-off-by: Stefan Roese <sr@denx.de>

diff --git a/board/amcc/acadia/cpr.c b/board/amcc/acadia/pll.c
similarity index 100%
rename from board/amcc/acadia/cpr.c
rename to board/amcc/acadia/pll.c