arm: ti: Fix Beaglebone black MMC after DTS update

After DTS sync with Linux kernel 5.8 this patch was included:
"ARM: dts: Move am33xx and am43xx mmc nodes to sdhci-omap driver"
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/arch/arm/boot/dts/am33xx-l4.dtsi?h=v5.9-rc2&id=0b4edf111870b83ea77b1d7e16b8ceac29f9f388

Current will not load any driver for MMC and not mount the rootfs.
Simple patch add "ti,am335-sdhci" to compability strings in ti_sdhci.c

Submitted by: oskar.holmlund@ohdata.se
Reported by: phk
X-MFC-With: 363853