ALSA: control: cage TLV_DB_RANGE_HEAD in kernel land because it was obsoleted

In commit bf1d1c9b ("ALSA: tlv: add DECLARE_TLV_DB_RANGE()"), the new
macro was added so that "dB range information can be specified without
having to count the items manually for TLV_DB_RANGE_HEAD()". In short,
TLV_DB_RANGE_HEAD macro was obsoleted.

In commit 46e860f7 ("ALSA: rename TLV-related macros so that they're
friendly to user applications"), TLV-related macros are exposed for
applications in user land to get content of data structured by
Type/Length/Value shape. The commit managed to expose TLV-related macros
as many as possible, while obsoleted TLV_DB_RANGE_HEAD() was included to
the list of exposed macros.

This situation brings some confusions to application developers because
they might think all exposed macros have their own purpose and useful for
applications.

For the reason, this commit moves TLV_DB_RANGE_HEAD macro from UAPI header
to a header for kernel land, again. The above commit is done within the
same development period for kernel 4.9, thus not published yet. This
commit might certainly brings no confusions to user land.

Reference: commit bf1d1c9b ("ALSA: tlv: add DECLARE_TLV_DB_RANGE()")
Reference: commit 46e860f7 ("ALSA: rename TLV-related macros so that they're friendly to user applications")
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>