mbedtls: Activate secp521r1 curve by default

Activate the secp521r1 ecliptic curve by default. This curve is allowed
by the CA/Browser forum, see
https://cabforum.org/wp-content/uploads/CA-Browser-Forum-BR-v2.0.1-redlined.pdf#page=110

This increases the size of libmbedtls12_2.28.5-1_aarch64_generic.ipk by
about 400 bytes:
Without:
252,696 libmbedtls12_2.28.5-1_aarch64_generic.ipk
With:
253,088 libmbedtls12_2.28.5-2_aarch64_generic.ipk

Fixes: #13774
Acked-by: Koen Vandeputte <[email protected]>
Signed-off-by: Hauke Mehrtens <[email protected]>

package/libs/mbedtls/Config.in

@@ -104,7 +104,7 @@ config MBEDTLS_ECP_DP_SECP384R1_ENABLED
 
 config MBEDTLS_ECP_DP_SECP521R1_ENABLED
 	bool "MBEDTLS_ECP_DP_SECP521R1_ENABLED"
-	default n
+	default y
 
 config MBEDTLS_ECP_DP_SECP192K1_ENABLED
 	bool "MBEDTLS_ECP_DP_SECP192K1_ENABLED"

package/libs/mbedtls/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=mbedtls
 PKG_VERSION:=2.28.5
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 PKG_BUILD_FLAGS:=no-mips16 gc-sections no-lto
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz