MLK-14620 env_sata: Fix build warning

MLK-14620 env_sata: Fix build warning

Fix below build warning by declaring sata_get_dev the in the part.h

common/env_sata.c: In function 'saveenv':
common/env_sata.c:70:9: warning: implicit declaration of function 'sata_get_dev' [-Wimplicit-function-declaration]
  sata = sata_get_dev(env_sata);
         ^
common/env_sata.c:70:7: warning: assignment makes pointer from integer without a cast [-Wint-conversion]
  sata = sata_get_dev(env_sata);
       ^
common/env_sata.c: In function 'env_relocate_spec':
common/env_sata.c:116:7: warning: assignment makes pointer from integer without a cast [-Wint-conversion]
  sata = sata_get_dev(env_sata);

Signed-off-by: Ye Li <ye.li@nxp.com>