devices: fs: Fix available_bytes() call
devices: fs: Fix available_bytes() call

This call was changed to not return a Result in "7f64f50
descriptor_utils: check for size overflow in new()".

BUG=b:136128319
TEST=build and run pjdfstests

Change-Id: Ibdc786b26ff35977723ba61c51e8cdf1b631edc8
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/1890581
Auto-Submit: Chirantan Ekbote <35787c0e27de5c48735e07f8324823b765e8bcbc@chromium.org>
Reviewed-by: Stephen Barber <7719587e4b5a49340661b214ec85602f3918d06f@chromium.org>
Reviewed-by: Daniel Verkamp <72bc170b46ec491f7bdd4359a1c0bfed274de40c@chromium.org>
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Commit-Queue: Chirantan Ekbote <35787c0e27de5c48735e07f8324823b765e8bcbc@chromium.org>

google/crosvm,google/crosvm,google/crosvm,google/crosvm