qcacmn: Fix minor pn_size init and index check

1. In hal reo setup initialize pn_size to avoid uninitialization
in default case.
2. In hal validate shadow register function, fix the check
for index as shadow_config array can take 0 to 35 as index values.

Change-Id: I8b729dc70053e333ef659ba38fb0c2f66cd8b35a
CRs-fixed: 2208799

hal/wifi3.0/hal_rx.c

@@ -73,7 +73,8 @@ void hal_reo_qdesc_setup(void *hal_soc, int tid, uint32_t ba_window_size,
 	uint32_t *reo_queue_desc = (uint32_t *)hw_qdesc_vaddr;
 	uint32_t *reo_queue_ext_desc;
 	uint32_t reg_val;
-	uint32_t pn_enable, pn_size;
+	uint32_t pn_enable;
+	uint32_t pn_size = 0;
 
 	qdf_mem_zero(hw_qdesc_vaddr, sizeof(struct rx_reo_queue));