driver core: Fix size calculation of symlink name for devlink_(add|remove)_symlinks()

driver core: Fix size calculation of symlink name for devlink_(add|remove)_symlinks()

devlink_(add|remove)_symlinks() kzalloc() memory to save symlink name
for both supplier and consumer, but do not explicitly take into account
consumer's prefix "consumer:", so cause disadvantages listed below:
1) it seems wrong for the algorithm to calculate memory size
2) readers maybe need to count characters one by one of both prefix
   strings to confirm calculated memory size
3) it is relatively easy to introduce new bug if either prefix string
   is modified in future
solved by taking into account consumer's prefix as well.

Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
Link: https://lore.kernel.org/r/20240712-devlink_fix-v3-1-fa1c5172ffc7@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>