s3c64xx: fix the compiler error and warning

s3c64xx: fix the compiler error and warning

This patch is fixing the following errors

s3c64xx.c:175: error: variable 's3c64xx_serial_drv' has initializer but incomplete type
s3c64xx.c:176: error: unknown field 'name' specified in initializer
s3c64xx.c:176: warning: excess elements in struct initializer
s3c64xx.c:176: warning: (near initialization for 's3c64xx_serial_drv')
s3c64xx.c:177: error: unknown field 'start' specified in initializer
s3c64xx.c:177: warning: excess elements in struct initializer
s3c64xx.c:177: warning: (near initialization for 's3c64xx_serial_drv')
s3c64xx.c:178: error: unknown field 'stop' specified in initializer
s3c64xx.c:178: warning: excess elements in struct initializer
s3c64xx.c:178: warning: (near initialization for 's3c64xx_serial_drv')
s3c64xx.c:179: error: unknown field 'setbrg' specified in initializer
s3c64xx.c:179: warning: excess elements in struct initializer
s3c64xx.c:179: warning: (near initialization for 's3c64xx_serial_drv')
s3c64xx.c:180: error: unknown field 'putc' specified in initializer
s3c64xx.c:180: warning: excess elements in struct initializer
s3c64xx.c:180: warning: (near initialization for 's3c64xx_serial_drv')
s3c64xx.c:181: error: unknown field 'puts' specified in initializer
s3c64xx.c:181: warning: excess elements in struct initializer
s3c64xx.c:181: warning: (near initialization for 's3c64xx_serial_drv')
s3c64xx.c:182: error: unknown field 'getc' specified in initializer
s3c64xx.c:182: warning: excess elements in struct initializer
s3c64xx.c:182: warning: (near initialization for 's3c64xx_serial_drv')
s3c64xx.c:183: error: unknown field 'tstc' specified in initializer
s3c64xx.c:183: warning: excess elements in struct initializer
s3c64xx.c:183: warning: (near initialization for 's3c64xx_serial_drv')
s3c64xx.c: In function 's3c64xx_serial_initialize':
s3c64xx.c:188: warning: implicit declaration of function 'serial_register'
s3c64xx.c: At top level:
s3c64xx.c:191: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'struct'

Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>
Acked-by: Marek Vasut <marex@denx.de>