ARM: at91: use proper asm syntax in pm_suspend

Compiling with the clang integrated assembler warns about
a recently added instruction:

<instantiation>:14:13: error: unknown token in expression
 ldr tmp1, =#0x00020010UL
arch/arm/mach-at91/pm_suspend.S:542:2: note: while in macro instantiation
 at91_plla_enable

Remove the extra '#' character that is not used for the 'ldr'
instruction when doing an indirect load of a constant.

Fixes: 4fd36e45 ("ARM: at91: pm: add plla disable/enable support for sam9x60")
Tested-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20210204160129.2249394-1-arnd@kernel.org

'
Signed-off-by: Arnd Bergmann <arnd@arndb.de>