media: mediatek: vcodec: fix decoder disable pm crash

In the Linux kernel, the following vulnerability has been resolved:

media: mediatek: vcodec: fix decoder disable pm crash

Can't call pm_runtime_disable when the architecture support sub device for
'dev->pm.dev' is NUll, or will get below crash log.

[ 10.771551] pc : _raw_spin_lock_irq+0x4c/0xa0
[ 10.771556] lr : __pm_runtime_disable+0x30/0x130
[ 10.771558] sp : ffffffc01e4cb800
[ 10.771559] x29: ffffffc01e4cb800 x28: ffffffdf082108a8
[ 10.771563] x27: ffffffc01e4cbd70 x26: ffffff8605df55f0
[ 10.771567] x25: 0000000000000002 x24: 0000000000000002
[ 10.771570] x23: ffffff85c0dc9c00 x22: 0000000000000001
[ 10.771573] x21: 0000000000000001 x20: 0000000000000000
[ 10.771577] x19: 00000000000000f4 x18: ffffffdf2e9fbe18
[ 10.771580] x17: 0000000000000000 x16: ffffffdf2df13c74
[ 10.771583] x15: 00000000000002ea x14: 0000000000000058
[ 10.771587] x13: ffffffdf2de1b62c x12: ffffffdf2e9e30e4
[ 10.771590] x11: 0000000000000000 x10: 0000000000000001
[ 10.771593] x9 : 0000000000000000 x8 : 00000000000000f4
[ 10.771596] x7 : 6bff6264632c6264 x6 : 0000000000008000
[ 10.771600] x5 : 0080000000000000 x4 : 0000000000000001
[ 10.771603] x3 : 0000000000000008 x2 : 0000000000000001
[ 10.771608] x1 : 0000000000000000 x0 : 00000000000000f4
[ 10.771613] Call trace:
[ 10.771617] _raw_spin_lock_irq+0x4c/0xa0
[ 10.771620] __pm_runtime_disable+0x30/0x130
[ 10.771657] mtk_vcodec_probe+0x69c/0x728 [mtk_vcodec_dec 800cc929d6631f79f9b273254c8db94d0d3500dc]
[ 10.771662] platform_drv_probe+0x9c/0xbc
[ 10.771665] really_probe+0x13c/0x3a0
[ 10.771668] driver_probe_device+0x84/0xc0
[ 10.771671] device_driver_attach+0x54/0x78