Revert "agm: Fix possible subtraction overflow error"

This reverts commit c11ee3f5a2a38fc4a4f27190c7e62e67150bffab.

Change-Id: Ic986018282b54c479e34f8033b66aba1ef0322fe
diff --git a/plugins/tinyalsa/src/agm_pcm_plugin.c b/plugins/tinyalsa/src/agm_pcm_plugin.c
index 1dac129..b8f375f 100644
--- a/plugins/tinyalsa/src/agm_pcm_plugin.c
+++ b/plugins/tinyalsa/src/agm_pcm_plugin.c
@@ -365,7 +365,7 @@
         new_hw_ptr = hw_base + pos;
 
         // Set delta_wall_clk_us only if cached wall clk is non-zero
-        if (wall_clk_msw != 0 || wall_clk_lsw != 0) {
+        if (priv->pos_buf->wall_clk_msw || priv->pos_buf->wall_clk_lsw) {
                 delta_wall_clk_us = (int64_t)((((uint64_t)wall_clk_msw) << 32 | wall_clk_lsw) -
                                         (((uint64_t)priv->pos_buf->wall_clk_msw) << 32 |
                                          priv->pos_buf->wall_clk_lsw));