am335x_hs_evm: Disable CONFIG_SPL_ENV_SUPPORT

The main uses of CONFIG_SPL_ENV_SUPPORT are for network support and for
disabling "Falcon Mode" support at run-time.  As this build enables
neither, remove this feature.

Cc: Andrew F. Davis <afd@ti.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Lokesh Vutla <lokeshvutla@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

configs/am335x_hs_evm_defconfig

@@ -18,6 +18,7 @@ CONFIG_VERSION_VARIABLE=y
 CONFIG_ARCH_MISC_INIT=y
 CONFIG_SPL=y
 CONFIG_SPL_STACK_R=y
+# CONFIG_SPL_ENV_SUPPORT is not set
 # CONFIG_SPL_EXT_SUPPORT is not set
 CONFIG_SPL_MTD_SUPPORT=y
 # CONFIG_SPL_YMODEM_SUPPORT is not set