p2020ds: add alternate boot bank support using the ngPIXIS FPGA

The Freescale P2020DS board uses a new type of PIXIS FPGA, called the ngPIXIS.
The ngPIXIS has one distinct new feature: the values of the on-board switches
can be selectively overridden with shadow registers.  This feature is used to
boot from a different NOR flash bank, instead of having a register dedicated
for this purpose.  Because the ngPIXIS is so different from the previous PIXIS,
a new file is introduced: ngpixis.c.

Also update the P2020DS checkboard() function to use the new macros defined
in the header file.

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/board/freescale/common/Makefile b/board/freescale/common/Makefile
index 02a824d..620eb16 100644
--- a/board/freescale/common/Makefile
+++ b/board/freescale/common/Makefile
@@ -33,6 +33,7 @@
 COBJS-${CONFIG_FSL_VIA}		+= cds_via.o
 COBJS-${CONFIG_FSL_DIU_FB}	+= fsl_diu_fb.o fsl_logo_bmp.o
 COBJS-${CONFIG_FSL_PIXIS}	+= pixis.o
+COBJS-${CONFIG_FSL_NGPIXIS}	+= ngpixis.o
 COBJS-${CONFIG_PQ_MDS_PIB}	+= pq-mds-pib.o
 COBJS-${CONFIG_ID_EEPROM}	+= sys_eeprom.o
 COBJS-${CONFIG_FSL_SGMII_RISER}	+= sgmii_riser.o