boot: zephyr: kconfig: enable dependencies of Mbed TLS Kconfig option

In Zephyr `MBEDTLS_KEY_EXCHANGE_RSA_ENABLED` doesn't enable its
dependencies anymore, so enable them along the enablement of this Kconfig
option.

Signed-off-by: Tomi Fontanilles <tomi.fontanilles@nordicsemi.no>

Author: tomi-font

boot/zephyr/Kconfig

@@ -213,6 +213,10 @@ config BOOT_SIGNATURE_TYPE_RSA
 	select BOOT_USE_MBEDTLS
 	select MBEDTLS
 	select MBEDTLS_ASN1_PARSE_C if MBEDTLS_BUILTIN
+	select MBEDTLS_MD if MBEDTLS_BUILTIN
+	select MBEDTLS_RSA_C if MBEDTLS_BUILTIN
+	select MBEDTLS_PKCS1_V15 if MBEDTLS_BUILTIN
+	select MBEDTLS_PKCS1_V21 if MBEDTLS_BUILTIN
 	select MBEDTLS_KEY_EXCHANGE_RSA_ENABLED if MBEDTLS_BUILTIN
 	select BOOT_ENCRYPTION_SUPPORT
 	select BOOT_IMG_HASH_ALG_SHA256_ALLOW