env: Rework ENV_IS_EMBEDDED and related logic slightly

- Drop CONFIG_BUILD_ENVCRC as this is never set directly but instead
  means ENV_IS_EMBEDDED, so reference that in code and rename the Makefile
  usage to BUILD_ENVCRC.
- Remove extra-$(CONFIG_ENV_IS_EMBEDDED) line as it could never be true,
  and likely why there is an extra- line for CONFIG_ENV_IS_IN_FLASH (the
  only use case today of embedded environments).
- With these slight changes we can then see that using the calculated
  symbol of ENV_IS_EMBEDDED is the right thing to use in any code which
  needs to know this situation and can remove CONFIG_ENV_IS_EMBEDDED
  entirely.

Signed-off-by: Tom Rini <trini@konsulko.com>

tools/Makefile

@@ -36,21 +36,20 @@ endif
 subdir-$(HOST_TOOLS_ALL) += gdb
 
 # Merge all the different vars for envcrc into one
-ENVCRC-$(CONFIG_ENV_IS_EMBEDDED) = y
 ENVCRC-$(CONFIG_ENV_IS_IN_EEPROM) = y
 ENVCRC-$(CONFIG_ENV_IS_IN_FLASH) = y
 ENVCRC-$(CONFIG_ENV_IS_IN_ONENAND) = y
 ENVCRC-$(CONFIG_ENV_IS_IN_NAND) = y
 ENVCRC-$(CONFIG_ENV_IS_IN_NVRAM) = y
 ENVCRC-$(CONFIG_ENV_IS_IN_SPI_FLASH) = y
-CONFIG_BUILD_ENVCRC ?= $(ENVCRC-y)
+BUILD_ENVCRC ?= $(ENVCRC-y)
 
 hostprogs-$(CONFIG_SPL_GENERATE_ATMEL_PMECC_HEADER) += atmel_pmecc_params
 
 hostprogs-$(CONFIG_VIDEO_LOGO) += bmp_logo
 HOSTCFLAGS_bmp_logo.o := -pedantic
 
-hostprogs-$(CONFIG_BUILD_ENVCRC) += envcrc
+hostprogs-$(BUILD_ENVCRC) += envcrc
 envcrc-objs := envcrc.o lib/crc32.o env/embedded.o lib/sha1.o
 
 hostprogs-$(CONFIG_CMD_NET) += gen_eth_addr