[POWERPC] 4xx: Fix Haleakala PCIe compatibility problem in dts

Since the 4xx PCIe driver checks for 405ex compatibility, the
PCIe interface was not detected as it is currently defined as
"405exr" compatible. This patch changes it to "405ex".

The 405EX and 405EXr are identical exept that the 2nd PCIe and the
2nd EMAC interfaces are missing.

Signed-off-by: Stefan Roese <sr@denx.de>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>