community/ffmpeg: re-enable asm on arm*

FFmpeg is pretty much unusable with --disable-asm on arm*.
At some point, ASM was disabled on arm* because FFmpeg required
text relocations. That does no longer seem to be the case.

The package builds just fine on arm* without --disable-asm
(without triggering the textrels check) and everything runs much faster.
8 jobs for !1971 with ffmpeg-arm-asm in 8 minutes and 55 seconds (queued for 1 second)
latest detached
Status Job ID Name Coverage
  Lint
passed #20987
docker-alpine x86_64
lint

00:01:00

 
  Build
passed #20992
docker-alpine ci-build aarch64
build-aarch64

00:03:47

passed #20993
docker-alpine ci-build armv7
build-armv7

00:03:36

passed #20991
docker-alpine ci-build ppc64le
build-ppc64le

00:07:23

passed #20994
s390x ci-build docker-alpine
build-s390x

00:06:47

passed #20989
docker-alpine ci-build x86
build-x86

00:02:33

passed #20988
docker-alpine ci-build x86_64
build-x86_64

00:01:33

failed #20990
docker-alpine ci-build s390x
build-s390x

00:00:32