ppc4xx: (Re-)Enable CONFIG_PCI_PNP on AMCC 440EPx Sequoia

The 440EPx has a problem when the PCI_CACHE_LINE_SIZE register is
set to non-zero, because it doesn't support MRM (memory-read-
multiple) correctly. We now added the possibility to configure
this register in the board config file, so that the default value
of 8 can be overridden.

Here the details of this patch:

o drivers_pci_auto.c: introduce CFG_PCI_CACHE_LINE_SIZE to allow
  board-specific settings. As an example the sequoia board requires 0.
  Idea from Stefan Roese <sr@denx.de>.
o board/amcc/sequoia/init.S: add a TLB mapping at 0xE8000000 for the
  PCI IO-space. Obtained from Stefan Roese <sr@denx.de>.
o include/configs/sequoia.h: turn CONFIG_PCI_PNP back on and set
  CFG_PCI_CACHE_LINE_SIZE to 0.

Signed-off-by: Gary Jennejohn <garyj@denx.de>
Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/board/amcc/sequoia/init.S b/board/amcc/sequoia/init.S
index 45bcd4b..5fe3af9 100644
--- a/board/amcc/sequoia/init.S
+++ b/board/amcc/sequoia/init.S
@@ -126,6 +126,9 @@
 	/* TLB-entry for peripherals */
 	tlbentry( 0xEF000000, SZ_16M, 0xEF000000, 1, AC_R|AC_W|AC_X|SA_G|SA_I)
 
+	/* TLB-entry PCI IO Space - from sr@denx.de */
+	tlbentry(0xE8000000, SZ_64K, 0xE8000000, 1, AC_R|AC_W|AC_X|SA_G|SA_I)
+
 	tlbtab_end
 
 #if defined(CONFIG_NAND_U_BOOT) && !defined(CONFIG_NAND_SPL)