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.h b/include/tinycrypt/ecc.h
index ede7544..37a7ef1 100644
--- a/include/tinycrypt/ecc.h
+++ b/include/tinycrypt/ecc.h
@@ -68,7 +68,7 @@
  *
  */
 
-#if defined(MBEDTLS_USE_UECC)
+#if defined(MBEDTLS_USE_TINYCRYPT)
 #ifndef __TC_UECC_H__
 #define __TC_UECC_H__
 
@@ -544,4 +544,4 @@
 #endif
 
 #endif /* __TC_UECC_H__ */
-#endif /* MBEDTLS_USE_UECC */
+#endif /* MBEDTLS_USE_TINYCRYPT */