wifi: rtl8xxxu: Fix RTL8188EU firmware upload block size

A user reports that the firmware upload consistently fails when it's
uploaded in chunks of 128 bytes, but it works when uploaded in chunks
of 196 bytes. The official driver uses 196 bytes also.

Link: https://github.com/a5a5aa555oo/rtl8xxxu/issues/2


Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/cba8e2f2-32c4-4174-90ba-0219f29dbdde@gmail.com