Add hi3516ev300_lite_xm-85h50ai device profile (XiongMai, motorized zoom+focus) (#141)

XiongMai's 85H50AI: hi3516ev300 + imx335 with a motorized zoom/focus
module whose MCU shares /dev/ttyAMA0 with the serial console at 115200,
speaking the XM near-Pelco protocol (majestic-webui's btzoom-xm).
Proven on a lab unit driven end to end through the WebUI
(majestic-webui#227).

The defconfig is a byte-copy of firmware's hi3516ev300_lite_defconfig.
customizer.sh (first boot) sets sensor imx335, the upgrade URL, and the
PTZ trio — ptz_control pelco-xm, ptz_port /dev/ttyAMA0, ptz_caps
'zoom focus' (majestic-webui#261) — and deletes the getty line from
/etc/inittab: the MCU owns the console UART. The edit lands in the
overlay and heals itself (an upgrade that wipes the overlay wipes
/etc/custom.ok too, so the script re-runs). S01printk quiets runtime
kernel messages that would drip onto the PTZ wire. The required
hi3516ev300_lite excludes list prunes every non-imx335 sensor blob,
generated from the live lite image so no entry is stale on arrival.

README.md

@@ -90,6 +90,7 @@ Vixand IVG-G6S-W         GK7205V300   IMX335    ATBM6032i_USB    NOR_16M   w/ext
 VStarcam C43S(B)         SSC333       JXF37     MT7601U_USB      NOR_16M   in progress
 VStarcam CS55            T31N         GC2053    RTL8188FU_USB    NOR_16M   in progress
 VStarcam C8622           T23N         SC2336P   AIC8800DL_?      NOR_8M    **INIT** - in progress
+XiongMai 85H50AI         HI3516EV300  IMX335    -                NOR_8M    testing, motorized zoom+focus (pelco-xm)
 VStarcam C8892WIP        HI3518EV200  AR0237    MT7601U_USB      NOR_16M   done
 VStarcam C8896WIP        GK7102C_A    GC2033    RTL8189ES_SDIO   NOR_8M    wip
 Wansview Q5 1080p        T21Z         OV2735B   RTL8188FU_USB    NOR_16M   in progress