Consistently use the name tinycrypt over uecc

We called in tinycrypt in the file names, but uecc in config.h, all.sh and
other places, which could be confusing. Just use tinycrypt everywhere because
that's the name of the project and repo where we took the files.

The changes were made using the following commands (with GNU sed and zsh):

sed -i 's/uecc/tinycrypt/g' **/*.[ch] tests/scripts/all.sh
sed -i 's/MBEDTLS_USE_UECC/MBEDTLS_USE_TINYCRYPT/g' **/*.[ch] tests/scripts/all.sh scripts/config.pl
diff --git a/include/tinycrypt/ecc_dh.h b/include/tinycrypt/ecc_dh.h
index 18a4fd2..c680a77 100644
--- a/include/tinycrypt/ecc_dh.h
+++ b/include/tinycrypt/ecc_dh.h
@@ -66,7 +66,7 @@
  *  Security: The curve NIST p-256 provides approximately 128 bits of security.
  */
 
-#if defined(MBEDTLS_USE_UECC)
+#if defined(MBEDTLS_USE_TINYCRYPT)
 #ifndef __TC_ECC_DH_H__
 #define __TC_ECC_DH_H__
 
@@ -130,4 +130,4 @@
 #endif
 
 #endif /* __TC_ECC_DH_H__ */
-#endif /* MBEDTLS_USE_UECC */
+#endif /* MBEDTLS_USE_TINYCRYPT */