tty: msm_smd_tty: Remove useless NULL checks

tty: msm_smd_tty: Remove useless NULL checks

Clang warns:

../drivers/tty/serial/msm_smd_tty.c:371:19: warning: address of array
'smd_tty[n].dev_name' will always evaluate to 'true'
[-Wpointer-bool-conversion]
                if (!smd_tty[n].dev_name)
                    ~~~~~~~~~~~~^~~~~~~~
../drivers/tty/serial/msm_smd_tty.c:505:39: warning: address of array
'smd_tty[n].ch_name' will always evaluate to 'true'
[-Wpointer-bool-conversion]
        if (n >= MAX_SMD_TTYS || !smd_tty[n].ch_name)
                                 ~~~~~~~~~~~~^~~~~~~
2 warnings generated.

Fixes: 21753c44f4e6 ("drivers: tty: serial: Add snapshot of SMD_TTY Driver")
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>