pdump: fix default socket path

SOCKET_PATH_HOME is to specify environment variable "HOME",
so it should not contain "/pdump_sockets"  in the macro.
So removed "/pdump_sockets" from SOCKET_PATH_HOME and
SOCKET_PATH_VAR_RUN. New changes will create pdump sockets under
/var/run/.dpdk/pdump_sockets for root users and
under HOME/.dpdk/pdump_sockets for non root users.
Changes are done in pdump_get_socket_path() to accommodate
new socket path changes.

Fixes: 278f945402c5 ("pdump: add new library for packet capture")

Signed-off-by: Reshma Pattan <reshma.pattan@intel.com>
Acked-by: John McNamara <john.mcnamara@intel.com>