Staging: rtl8192e: Declare variable with static

Fixed sparse warning:
"'dm_rx_path_sel_table' was not declared. Should it be static?"
As dm_rx_path_sel_table is used only in rtl_dm.c it should be static.
Signed-off-by: Ariel Silver <arielsilver77@gmail.com>
Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
Link: https://lore.kernel.org/r/20240309174722.3463-1-arielsilver77@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8192e/rtl8192e/rtl_dm.c

@@ -144,7 +144,7 @@ const u8 dm_cck_tx_bb_gain_ch14[CCK_TX_BB_GAIN_TABLE_LEN][8] = {
 /*------------------------Define global variable-----------------------------*/
 struct dig_t dm_digtable;
 
-struct drx_path_sel dm_rx_path_sel_table;
+static struct drx_path_sel dm_rx_path_sel_table;
 /*------------------------Define global variable-----------------------------*/