pkwrite: minor code reshape

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/library/pkwrite.c b/library/pkwrite.c
index c7eb114..bd592f4 100644
--- a/library/pkwrite.c
+++ b/library/pkwrite.c
@@ -44,15 +44,13 @@
 #if defined(MBEDTLS_PK_USE_PSA_EC_DATA)
 #define PK_MAX_EC_PUBLIC_KEY_SIZE       PSA_EXPORT_PUBLIC_KEY_MAX_SIZE
 #define PK_MAX_EC_KEY_PAIR_SIZE         MBEDTLS_PSA_MAX_EC_KEY_PAIR_LENGTH
-#else
-#if defined(MBEDTLS_USE_PSA_CRYPTO)
+#elif defined(MBEDTLS_USE_PSA_CRYPTO)
 #define PK_MAX_EC_PUBLIC_KEY_SIZE       PSA_EXPORT_PUBLIC_KEY_MAX_SIZE
 #define PK_MAX_EC_KEY_PAIR_SIZE         MBEDTLS_PSA_MAX_EC_KEY_PAIR_LENGTH
 #else
 #define PK_MAX_EC_PUBLIC_KEY_SIZE       MBEDTLS_ECP_MAX_PT_LEN
 #define PK_MAX_EC_KEY_PAIR_SIZE         MBEDTLS_ECP_MAX_BYTES
 #endif
-#endif
 
 /******************************************************************************
  * Internal functions for RSA keys.