opkg: fix stray \ warnings with grep-3.8
We simply grep for "src/". So no need for "\/".
Furthermore, since grep-3.8 this creates warnings.
As written in the grep-3.8 announcement:
Regular expressions with stray backslashes now cause warnings, as
their unspecified behavior can lead to unexpected results.
For example, '\a' and 'a' are not always equivalent
<https://bugs.gnu.org/39678>.
Fixes a warning during the first boot:
grep: warning: stray \ before /
Signed-off-by: Georgi Valkov <[email protected]>
Georgi Valkov