components/bt: Add api to query the number of available buffers for the current connection

components/bt/host/bluedroid/stack/l2cap/include/l2c_int.h

@@ -74,6 +74,8 @@
 #define L2CAP_DEFAULT_MONITOR_TOUT   12000        /* 12000 milliseconds */
 #define L2CAP_FCR_ACK_TOUT           200          /* 200 milliseconds */
 
+#define L2CAP_CACHE_ATT_ACL_NUM      10
+
 /* Define the possible L2CAP channel states. The names of
 ** the states may seem a bit strange, but they are taken from
 ** the Bluetooth specification.
@@ -165,6 +167,9 @@ typedef enum {
 
 #define L2CAP_MAX_FCR_CFG_TRIES         2       /* Config attempts before disconnecting */
 
+#ifndef MIN
+#define MIN(a, b) (((a) < (b)) ? (a) : (b))
+#endif
 typedef uint8_t tL2C_BLE_FIXED_CHNLS_MASK;
 
 typedef struct {