ARM: dts: at91: sama5d3 Xplained: don't disable hsmci regulator

If enabling the hsmci regulator on card detection, the board can reboot
on sd card insertion. Keeping the regulator always enabled fixes this
issue.

Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Fixes: 1b53e341

 ("ARM: at91/dt: sama5d3 xplained: add fixed regulator for vmmc0")
Cc: stable@vger.kernel.org #4.3 and later
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>