Audio: Format: Add macro to convert fraction to double

The usage of Q_CONVERT_QTOF() causes build issue with llvm
toolchain when assigned to a double type in ztest code:

error: implicit conversion increases floating-point precision:
'float' to 'double' [-Werror,-Wdouble-promotion]

Since a double is needed to fully match the accuracy of 32 bit
fraction, a new macro Q_CONVERT_QTOD() is added for the purpose.

Signed-off-by: Seppo Ingalsuo <seppo.ingalsuo@linux.intel.com>

Author: singalsu

src/include/sof/audio/format.h

@@ -70,6 +70,9 @@
 /* Convert fractional Qnx.ny number x to float */
 #define Q_CONVERT_QTOF(x, ny) ((float)(x) / ((int64_t)1 << (ny)))
 
+/* Convert fractional Qnx.ny number x to double */
+#define Q_CONVERT_QTOD(x, ny) ((double)(x) / ((int64_t)1 << (ny)))
+
 /* A more clever macro for Q-shifts */
 #define Q_SHIFT(x, src_q, dst_q) ((x) >> ((src_q) - (dst_q)))
 #define Q_SHIFT_RND(x, src_q, dst_q) \