serial: fix driver_name conflicts

Some drivers are using too generic "serial" name for driver_name, this
might cause issues, like this:

Freescale QUICC Engine UART device driver
proc_dir_entry 'serial' already registered
Call Trace:
[cf82de50] [c0007f7c] show_stack+0x4c/0x1ac (unreliable)
[cf82de90] [c00b03fc] proc_register+0xfc/0x1ac
[cf82dec0] [c00b05c8] create_proc_entry+0x60/0xac
[cf82dee0] [c00b23dc] proc_tty_register_driver+0x60/0x98
[cf82def0] [c016dbd8] tty_register_driver+0x1b4/0x228
[cf82df20] [c0184d70] uart_register_driver+0x144/0x194
[cf82df40] [c030a378] ucc_uart_init+0x2c/0x94
[cf82df50] [c02f21a0] kernel_init+0x98/0x27c
[cf82dff0] [c000fa74] kernel_thread+0x44/0x60

^^ The board is using ucc_uart.c and 8250.c, both registered as
   "serial".

This patch fixes two drivers that are using "serial" for driver_name and
not "ttyS" for dev_name.  Drivers that are using "ttyS" for dev_name, will
conflict anyway, so we don't bother with these.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Acked-by: Alan Cox <alan@redhat.com>
Acked-By: Timur Tabi <timur@freescale.com>
Acked-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>