qemu: enabling the alsa driver needs alsa in DEPENDS, add it

qemu: enabling the alsa driver needs alsa in DEPENDS, add it

This fixes:

| + /OE/tentacle/build/tmp-angstrom_2010_x/work/x86_64-linux/qemu-native-0.13.0-r1/qemu-0.13.0/configure --prefix=/OE/tentacle/build/tmp-angstrom_2010_x/sysroots/x86_64-linux/usr --target-list=arm-linux-user,arm-softmmu,i386-linux-user,i386-softmmu,x86_64-linux-user,x86_64-softmmu,mips-linux-user,mips-softmmu,ppc-linux-user,ppc-softmmu,mipsel-linux-user --disable-werror --disable-vnc-tls --enable-kvm --audio-drv-list=oss,alsa --audio-card-list=ac97,es1370
|
| Error: alsa check failed
| Make sure to have the alsa libs and headers installed.

Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>