[submodule]: update sonic-utilities

* d0f8091 2020-03-22 | Revert "add support for MCLAG (sonic-net#453)" (sonic-net#849) (HEAD -> master, origin/master, origin/HEAD) [lguohan]
* 6f54e8c 2020-03-22 | Revert "return list for _get_optional_services() (sonic-net#822)" (sonic-net#848) [lguohan]
* f1c79d5 2020-03-22 | return list for _get_optional_services() (sonic-net#822) (HEAD -> master, origin/master, origin/HEAD) [shine4chen]
* 28ea21a 2020-03-21 | Fix kernel panic for irq after fast-reboot (sonic-net#823) [byu343]
* 727b499 2020-03-22 | [decode-syseeprom] fix getattribute check for sime platforms (sonic-net#835) [Mykola F]
* db78cb6 2020-03-21 | Update Command Reference with sFlow section (sonic-net#841) [padmanarayana]
* 780673c 2020-03-21 | explicitly specify command with underscores (sonic-net#846) [lguohan]
* 07dc201 2020-03-21 | [db_migrator]Do DB migration for buffer pool size change on Mellanox platform (sonic-net#833) [Kebo Liu]
* 9a94955 2020-03-20 | [sonic_installer] Enable ARM64 arch (sonic-net#811) [arheneus@marvell.com]
* 92b30c2 2020-03-18 | [config]: add syslog messages to config load_minigraph/reload (sonic-net#843) [lguohan]
* 4389ffe 2020-03-17 | [intfutil] set speed to 0 when interface speed is not available (sonic-net#839) [Ying Xie]
* 45c6c68 2020-03-17 | [Mellanox] add document for thermal control related cli (sonic-net#832) [Junchao-Mellanox]
* 7105400 2020-03-12 | Add kdump support for Aboot platforms (sonic-net#824) [byu343]
* c5c5ffc 2020-03-01 | [fwutil]: Set default socket timeout for FW download to 30 sec. (sonic-net#821) [Nazarii Hnydyn]
* 81c5930 2020-03-01 | Update config/show to include PFC Watchdog commands (sonic-net#736) [Andriy Moroz]
* 66e9dfb 2020-02-28 | [MultiDB] sonic-utilities - replace redis-cli/redis-dump with sonic-db-cli/sonic-db-dump (sonic-net#810) [Dong Zhang]
* 8aea564 2020-02-24 | add support for MCLAG (sonic-net#453) [shine4chen]
* 118620f 2020-02-23 | [reboot] make sure the reboot happens even if platform reboot failed (sonic-net#819) [Ying Xie]
* 40eff82 2020-02-22 | Multi-Db changes for NAT feature. (sonic-net#818) [Akhilesh Samineni]
* a4cb4dd 2020-02-21 | [Command-Reference.md] Unify Usage statments and Examples (including sample prompts) (sonic-net#816) [Joe LeVeque]

Signed-off-by: Guohan Lu <lguohan@gmail.com>