env: Enable getenv_f() for SPL_BUILD

With this patch, getenv_f() can be included easily into the SPL
binary. With this, SPL boards can now use getenv_f() to read
environment variables (e.g. to detect if the OS or U-Boot shall
be executed).

In the approach this is done for env stored in NOR flash, as this
will be used by an upcoming MPC5200 board port.

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

common/Makefile

@@ -195,6 +195,9 @@ COBJS-$(CONFIG_CMD_DFU) += cmd_dfu.o
 endif
 
 ifdef CONFIG_SPL_BUILD
+COBJS-y += cmd_nvedit.o
+COBJS-y += env_common.o
+COBJS-$(CONFIG_ENV_IS_IN_FLASH) += env_flash.o
 COBJS-$(CONFIG_SPL_YMODEM_SUPPORT) += xyzModem.o
 COBJS-$(CONFIG_SPL_NET_SUPPORT) += cmd_nvedit.o
 COBJS-$(CONFIG_SPL_NET_SUPPORT) += env_common.o