powerpc: mpc85xx: Do not build errata command in SPL

The errata command is useless in SPL, so don't build it. This fixes
multiple build failures on PowerPC.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: York Sun <york.sun@nxp.com>
Fixes: 92623672 ("fsl: usb: make errata function common for PPC and ARM")

arch/powerpc/cpu/mpc85xx/Makefile

@@ -26,7 +26,9 @@ else
 
 obj-$(CONFIG_MP)	+= release.o
 
+ifndef CONFIG_SPL_BUILD
 obj-$(CONFIG_CMD_ERRATA) += cmd_errata.o
+endif
 obj-$(CONFIG_CPM2)	+= commproc.o
 
 obj-$(CONFIG_CPM2)	+= ether_fcc.o