Add the Denali disk driver.

Begin enumerating information from the PCI structure and HBA AHCI
structures.

Currently the PCI structure address is hardcoded but it should be
passed via a capability from the init process in the future.

lib/mammoth/include/mammoth/debug.h

@@ -10,3 +10,11 @@ void dbgln(const char* fmt, ...);
 void check(uint64_t);
 
 void crash(const char*, z_err_t);
+
+#define RET_ERR(expr)        \
+  {                          \
+    z_err_t _tmp_err = expr; \
+    if (_tmp_err != Z_OK) {  \
+      return _tmp_err;       \
+    }                        \
+  }