env: make file-scope env_ptr variables static

The combination ENV_IS_IN_NVRAM=y, ENV_IS_IN_REMOTE=y fails to build:

env/remote.o:/mnt/ext4/devel/u-boot/env/remote.c:17: multiple definition of `env_ptr'
env/nvram.o:/mnt/ext4/devel/u-boot/env/nvram.c:41: first defined here

It's not necessarily a meaningful combination, but for build-testing
it's nice to be able to enable most ENV_IS_IN_* at the same time, and
since these env_ptr are not declared anywhere, they really have no
reason to have external linkage.

nand.c and flash.c similarly already define file-scope static env_ptr
variables.
Signed-off-by: NRasmus Villemoes <rasmus.villemoes@prevas.dk>

env/nvram.c

@@ -38,7 +38,7 @@ DECLARE_GLOBAL_DATA_PTR;
 extern void *nvram_read(void *dest, const long src, size_t count);
 extern void nvram_write(long dest, const void *src, size_t count);
 #else
-env_t *env_ptr = (env_t *)CONFIG_ENV_ADDR;
+static env_t *env_ptr = (env_t *)CONFIG_ENV_ADDR;
 #endif
 
 #ifdef CONFIG_SYS_NVRAM_ACCESS_ROUTINE

env/remote.c

@@ -12,9 +12,9 @@
 #include <u-boot/crc.h>
 
 #ifdef ENV_IS_EMBEDDED
-env_t *env_ptr = &environment;
+static env_t *env_ptr = &environment;
 #else /* ! ENV_IS_EMBEDDED */
-env_t *env_ptr = (env_t *)CONFIG_ENV_ADDR;
+static env_t *env_ptr = (env_t *)CONFIG_ENV_ADDR;
 #endif /* ENV_IS_EMBEDDED */
 
 DECLARE_GLOBAL_DATA_PTR;